Patent Application
20070007637
The present invention generally relates to an electrical interconnect scheme for a substrate assembly that is preferably assembled at least in part using fluidic self assembly and, more particularly, to defining electrical interconnects on an upper surface of a receptor layer that is at least substantially coplanar with an upper surface of blocks that are disposed in holes extending through the receptor layer, thereby alleviating the need for vias to make the electrical interconnection to such blocks.
A process that is referred to as “fluidic self assembly” is described in U.S. Pat. No. 5,545,291, that is entitled “METHOD FOR FABRICATING SELF-ASSEMBLING MICROSTRUCTURES,”, and that issued on Aug. 13, 1996; U.S. Pat. No. 5,904,545, that is entitled “APPARATUS FOR FABRICATING SELF-ASSEMBLING MICROSTRUCTURES,”, and that issued on May 18, 1999; U.S. Pat. No. 6,291,896, that is entitled “FUNCTIONALLY SYMMETRIC INTEGRATED CIRCUIT DIE,” and that issued on Sep. 18, 2001; and U.S. Pat. No. 6,657,289, that is entitled “APPARATUS RELATING TO BLOCK CONFIGURATIONS AND FLUIDIC SELF-ASSEMBLY PROCESSES,” and that issued on Dec. 2, 2003, the disclosures of which are incorporated by reference in their entirety herein. Generally, fluidic self assembly entails forming a plurality of shaped blocks. Each shaped block has at least one electrical component (e.g., an active electrical component, a passive electrical component). These plurality of blocks are disposed in an appropriate fluid that is then directed over a substrate having a plurality of concave recesses formed therein. The plurality of blocks and concave recesses are complimentarily shaped such that one of the blocks may assume a desired position in one of the recesses. Typically a number of the blocks are each deposited in a concave recess on the substrate as the substrate is exposed to the fluid.
Electrical interconnects are formed after a desired number of blocks have been positioned within the concave recesses on the substrate. One way in which this may be done is to form a planarizing layer over the substrate with a plurality of plurality of blocks being disposed in their own substrate recess. This planarizing layer at least assists in retaining the blocks within their respective substrate recess, and further provides a flat surface on which electrical interconnects may be formed. One or more vias must be cut open down through this planarizing layer to an electrical contact or terminal (e.g., a bond or a bonding pad) of the corresponding block. Typically these vias are filled with one type of material. Thereafter, a different material is used to define one or more electrical interconnects (e.g., a line, wire, or trace) on the upper surface of the planarizing layer. One or more masks (e.g., photolithographic) may be used to define the various vias and electrical interconnects. This electrical interconnect scheme thereby requires a number of process steps, which of course adds to both the complexity and cost of the overall fabrication process (e.g., fabrication of one or more masks; deposition of one or more layers of photoresist; alignment of one or more masks; development of the photoresist; etching; stripping of the photoresist). A screen printing processes may also be used to define the electrical interconnects.
A first aspect of the present invention is embodied by what may be characterized as a substrate assembly. The substrate assembly includes a receptor layer, a first block, a bonding layer, and a first electrical interconnect. The receptor layer includes at least one hole (hereafter a first hole) that extends between its oppositely disposed first and second surfaces. The first block includes a first electrical terminal and is disposed within the first hole of the receptor layer. A bonding material interfaces with the second surface of the receptor layer, while a first electrical interconnect extends along the oppositely disposed first surface of the receptor layer and to the first electrical terminal of the first block.
Various refinements exist of the features noted in relation to the first aspect of the present invention. Further features may also be incorporated in the first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. The receptor layer may include any appropriate number of first holes. Each first hole may be of the same size, shape, and configuration, although such need not be the case (e.g., a first group of first holes may be of one size, shape, and/or configuration, while another group of first holes may be of a different size, shape, and/or configuration). A separate first block may be disposed in each of multiple first holes through the receptor layer, such that the substrate assembly may include multiple first blocks, each being disposed in their own first hole through the receptor layer. Although each first block could be of the same size, shape, and configuration, such need not be the case. Each first block may be complementarily-shaped so as to be disposed within a first hole in a particular orientation, although such need not be the case.
The receptor layer may be of any appropriate configuration. In one embodiment, the receptor layer is a flexible structure. In another embodiment, the receptor layer is a rigid structure. The receptor layer also may be formed of any appropriate material or combination of materials, but will typically be a dielectric as the first electrical interconnect is disposed directly on its first surface. The first electrical interconnect may be of any appropriate type, size, shape, and configuration (e.g., a line, trace), and the substrate assembly may include any appropriate number of first electrical interconnects and in any appropriate arrangement.
Each first block may provide any appropriate functionality, but will typically include at least one electrical component. Herein, “electrical component” means any component that sends or transmits an electrical signal, that receives an electrical signal, or both, including without limitation a single circuit element. Any number of electrical components may be included on each first block and in any appropriate arrangement. The first block may also include any appropriate number of first electrical terminals.
The first electrical terminal associated with the first block may be located on a first surface of the first block. This first surface of the first block may be at least substantially coplanar with the first surface of the receptor layer on which the first electrical interconnect is formed. The first block may include a second surface that is disposed directly opposite of its first surface. The bonding material may interface with the entirety of second surface of the first block. The first block also may be characterized as being seated within the bonding material. For instance, the first block may create a depression in the bonding material during assembly. Another characterization is that the first block has first and second ends, where the first end has the first electrical terminal and is disposed at least substantially coplanar with the first surface of the receptor layer on which the first electrical interconnect is disposed, and where at least the second end of the first block is embedded within the bonding material.
An annular first sidewall of the receptor layer may define the first hole, and the first block may include an annular sidewall. At least part of the sidewall of the first block may be spaced from the first sidewall that defines the first hole through the receptor layer. Preferably, any gap between the first sidewall of the receptor layer and the sidewall of the first block within the first hole is occupied by bonding material. One embodiment has the entirety of the first block being spaced from the annular first sidewall that defines the first hole through the receptor layer. In this case, the entirety of the space between the first block and the annular first sidewall is preferably occupied by bonding material. Another embodiment has an annular portion of the first block (e.g., an uppermost portion of a sidewall of the first block) being in contact with part of the first sidewall that defines the first hole through the receptor layer (hereafter a “zero clearance fit”), with the remainder of the first block being spaced from this first sidewall. That is, the zero clearance relationship need not exist between all corresponding portions of the first sidewall and the perimeter of the first block (e.g., the entire first sidewall that defines the first hole through the receptor layer need not be contacted by the first block; the entire thickness of the first block need not contact the first sidewall that defines the first hole through the receptor layer). In this case as well, the entirety of any space between the annular first sidewall and the remainder of the first block within the first hole is preferably occupied by bonding material. Preferably, any gap between the receptor layer and all portions of the first block within the first hole are occupied by bonding material, including where this gap exists at the first surface of the receptor layer on which the first electrical interconnect is disposed. In this case, the bonding material that is disposed within this gap is also preferably coplanar with the first surface of the receptor layer on which the first electrical interconnect is disposed. This allows the first electrical interconnect to cross this “filled” gap to contact the first electrical terminal on the first block.
Any appropriate type of material or combination of materials may define the bonding material. The bonding material may also be in any appropriate form, including a solid, liquid, or paste. It may be desirable for the bonding material to be sufficiently viscous in one or more instances (e.g., prior to and/or during compression of the substrate assembly), and which may require a heat treatment of the bonding material. One embodiment has the bonding material in the form of an appropriate adhesive impregnated carrier (e.g., cloth, mesh, paper). This adhesive may be used to fill any gap between the receptor layer and the first block within the first hole, and further may secure the position of the first block relative to the receptor layer.
The substrate assembly may include any appropriate number of layers. In one embodiment, a backup layer is provided such that the bonding material is disposed or retained between the backup layer and the receptor layer. The backup layer may be of any appropriate material or combination of materials, and may be of any appropriate size, shape, and configuration. Similarly, a release layer or film may be removably disposed on the first surface of the receptor layer and on a corresponding surface of the first block. This release film may be used when placing the substrate assembly in compression to force bonding material into any gap between the receptor layer and the first block after it has been properly positioned within the first hole. Although the first electrical interconnect will typically be defined or formed after the release film has been removed, such need not always be the case. Another option would be to include such a release film on a portion of a structure that contacts the receptor layer in order to compress the substrate assembly in a manner that will be discussed in more detail below. A release film could be disposed on both the receptor layer and the above-noted structure. Yet another option would be to spray a release material on the receptor layer and/or the above-noted structure.
In a preferred embodiment, an upper surface of the receptor layer and an upper surface of the first block are at least substantially coplanar. There may or may not be a zero clearance fit between the receptor layer and the first block when positioned within the first hole. However, at least part of a first sidewall that defines the first hole through the receptor layer and a sidewall of the first block within the first hole are separated by a space, and bonding material occupies at least substantially all of this space. An electrical interconnect extending across the upper surface of the receptor layer may cross and be supported by the upper end of bonding material within the first hole prior to reaching the upper surface of the first block if there is a gap between an upper edge of the first block and an upper edge of the first hole through the receptor layer. Having the upper surface of the receptor layer, the upper surface of the first block, and the upper end of the bonding material within the first hole being coplanar allows at least substantially the entirety of the electrical interconnect to be supported and remain at an at least substantially constant elevation. However, a zero clearance relationship could exist between the receptor layer and the upper edge of the first block when positioned within the first hole such that the electrical interconnect need not “cross” a bonding material filled gap to progress from the upper surface of the receptor layer to the upper surface of the first block.
A second aspect of the present invention is embodied by a method for making a substrate assembly. The substrate assembly includes a receptor layer having a first hole. A first block is directed into the first hole from a first side of the receptor layer. A bonding layer is disposed on a second side of the receptor layer that is opposite the first side. That is, the first block is installed into the first hole from the side of the receptor layer that is opposite that which interfaces with the bonding layer. The receptor layer and bonding layer may be collectively referred to as a substrate. This substrate is compressed and a bonding material from the bonding layer is directed into a space between the first block and an annular sidewall of the receptor layer that defines the first hole in which the first block is positioned.
Various refinements exist of the features noted in relation to the second aspect of the present invention. Further features may also be incorporated in the second aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, the various features discussed above in relation to the first aspect may be utilized by or incorporated into this second aspect as well, individually or in any appropriate combination.
The first block may be directed into the first hole of the receptor layer in any appropriate manner (e.g., using a “pick and place” technology; robotically). More preferably this is done using what may be characterized as fluidic self assembly. In this case the first block is disposed within a fluid that is put into contact with at least the first side of the receptor layer such that the first block in effect may be carried by the fluid and allowed to “settle” into the first hole of the receptor layer. Stated another way, there may be a flow of sorts at least generally along a first surface of the receptor layer on its first side that allows the first block to be positioned within the first hole of the receptor layer. This “flow” may be of the first block through the fluid, or a flow of the fluid with the first block as well. Typically, a plurality of blocks will be disposed in a fluid to form a slurry, and at least the first side of the receptor layer will be exposed to this slurry. This of course encompasses having the receptor layer be totally submerged in the slurry. At least certain of these blocks and the first hole may be complementarily-shaped—that is, such that the first hole is shaped to accommodate receipt of one of these blocks and typically within a certain orientation within the first hole. It should be appreciated that typically the receptor layer will include a plurality of similarly-shaped first holes, each of which may then receive a single, complimentarily-shaped block in the noted manner.
In one embodiment where there is a zero clearance fit between the first block and the receptor layer when the first block is positioned within the first hole, the first block is positioned within the first hole from the first side of the receptor layer before the bonding layer is disposed on the second, opposite side of the receptor layer. Fluidic self assembly could thereby be used to position the first block within the first hole prior to assembling the bonding layer and receptor layer (e.g., the bonding layer could be attached to or formed on the second side of the receptor layer after fluidic self assembly has been completed). Another option would be for the bonding layer to be disposed on the second side of the receptor layer prior to positioning the first block within the first hole of the receptor layer. Fluidic self assembly could thereby be used to position the first block within the first hole after the bonding layer has already been formed on or attached to the second side of the receptor layer. The substrate could include one or more additional layers, including at the time of fluidic self assembly (e.g., a backup layer that “sandwiches” the bonding layer between the backup layer and the receptor layer).
The first block may be the same thickness as or thinner than the receptor layer. That is, a first surface of the first block initially may be at least substantially coplanar with or recessed relative to a first surface of the receptor layer on the first side of the receptor layer. Compression of the substrate may thereafter dispose the first surface of the receptor layer in at least substantially coplanar relation with the first surface of the first block. Generally, the bonding material of the bonding layer may “push” the first block within the first hole (toward the first side) such that its first surface is at least substantially coplanar with the first surface of the receptor layer. Compression of the substrate may also direct bonding material of the bonding layer into any gap between the receptor layer and the first block within the first hole. Preferably, any gap between the receptor layer and the first block within the first hole is at least substantially “filled” by bonding material of the bonding layer being forced into this gap by the compression of the substrate. This then provides an at least substantially planar and continuous surface along which electrical interconnects may extend (and also holds the first block in place). That is, one or more electrical interconnects may extend along the first surface of the receptor layer and onto the first surface of a first blocks without being unsupported across any gap between an upper edge of the first hole and an upper edge of the first block because of the existence of bonding material in this gap.
In the case where the receptor layer is thicker than the first block, the first hole may be “bigger around” or larger than any portion of the first block positioned therein (e.g., there is no zero clearance fit between the receptor layer and the first block in this instance). For instance, the maximum effective size of the first block may be less than the maximum effective size of the first hole at the first surface of the receptor layer. Stated another way, the perimeter of the first hole at a first surface of the receptor layer on its first side may be larger than the maximum perimeter of the first surface of the first block. Therefore, a gap will exist between at least part of the receptor layer and the first block when their respective first surfaces are disposed in at least substantially coplanar relation (including having an annular gap between the receptor layer and the first block). Again, preferably this gap is “filled” by bonding material of the bonding layer from the compression of the substrate.
The first block also may be thicker than the receptor layer. In this case a first surface of the receptor layer on its first side initially may be recessed relative to a first surface of the first block (e.g., the first block may initially “protrude” from the first surface of the receptor layer). Compression of the substrate may thereafter dispose the first surface of the receptor layer in at least substantially coplanar relation with the first surface of the first block. Generally, the first block may be “pressed down” into the bonding layer. This may form a depression within the bonding layer. Compression of the substrate may also direct bonding material of the bonding layer into any gap between the receptor layer and the first block within the first hole. Preferably, any gap between the receptor layer and the first block within the first hole is “filled” by bonding material of the bonding layer being forced into this gap by the compression of the substrate. This then provides a substantially planar and continuous surface along which electrical interconnects may extend. That is, one or more electrical interconnects may extend along the first surface of the receptor layer and onto the first surface of a first block without being unsupported across any gap between an upper edge of the first hole and an upper edge of the first block because of the existence of bonding material in this gap.
In the case where the receptor layer is thinner than the first block, the first hole again may be “bigger around” or larger than the first block positioned therein (e.g., there is no zero clearance fit between the receptor layer and the first block in this instance). For instance, the maximum effective size of the first block may be less than the maximum effective size of the first hole at the first side of the receptor layer. Stated another way, the perimeter of the first hole at a first surface of the receptor layer on its first side may be larger than the maximum perimeter of the first block. Therefore, a gap may exist between at least part of the receptor layer and the first block when disposed in at least substantially coplanar relation on the first side of the receptor layer (including having an annular gap between the receptor layer and the first block within the first hole). Again, preferably this gap is “filled” by bonding material of the bonding layer from the compression of the substrate.
In the case where the receptor layer is thinner than the first block, the first hole also may be the same size as or “smaller” than the first block positioned therein in at least some respect such that there is a zero clearance fit between the perimeter of the first block (at least at its upper edge) and the perimeter of the first hole in the receptor layer (at least at its upper edge). Preferably, no appreciable forces are required to dispose the first block within the first hole in the receptor layer to realize this zero clearance fit, although a press or interference fit relationship could exist between the first block and the receptor layer if warranted. In relation to the noted zero clearance fit, the maximum effective size of the first block may be the same as the maximum effective size of the first hole at the first side of the receptor layer, or the maximum effective size of the first block may be greater than the maximum effective size of the first hole at the first side of the receptor layer. Stated another way, the perimeter of the first hole at a first surface of the receptor layer on its first side may be the same as or smaller than the maximum perimeter of the first block. Therefore, an annular first portion of the first block may be in contact with the receptor layer at its first side prior to the substrate being compressed or after the substrate has been compressed. The result of the subsequent compression of the substrate is subject to a number of characterizations in this situation. One is that the compression may at least slightly deform the receptor layer (e.g., by enlarging at least part of the first hole somewhat). Another is that the compression provides a zero clearance fit between an annular first portion of the first block and a corresponding portion of the sidewall of the receptor layer that defines the first hole. The remainder of the sidewall of the receptor layer that defines the first hole may remain spaced from the first block within the first hole. Again, preferably bonding material of the bonding layer is forced into this gap by the compression of the substrate.
Any appropriate way of placing the substrate in compression may be utilized. It may be desirable to provide a release layer over the receptor layer and the first block prior to placing the substrate in compression. Once the substrate has been compressed, the release layer may be removed. Heat may be applied prior to and/or during the compression as well if desired/required for the bonding material of the bonding layer, including that which was directed into the first hole. Any appropriate way of heat treating the bonding material of the bonding layer may be undertaken. One or more materials for the bonding layer may be appropriate and may not require any heat treatment at all. In any case, the bonding material appropriately “fixes” the first block within the first hole of the receptor layer. For at least certain bonding materials, it may be desired to “capture” or sandwich the bonding layer between the receptor layer and a backup layer. This backup layer could then be part of the substrate that is compressed in accordance with the foregoing.
A third aspect of the present invention is embodied by a method for making a substrate assembly. The substrate assembly includes a receptor layer having first and second oppositely disposed surfaces, as well as a first hole that extends between these first and second surfaces. A first block is at least partially positioned in the first hole of the receptor layer. This first block includes a first electrical terminal on its first surface. A bonding layer is disposed on the second surface of the receptor layer. The receptor layer and bonding layer may be collectively referred to as a substrate. The substrate is compressed to dispose the first surface of the first block (having the first electrical terminal) at least substantially coplanar with the first surface of the receptor layer. A first electrical interconnect is formed on the first surface of the receptor layer and on the first surface of the first block, that again are disposed in at least substantially coplanar relation.
Various refinements exist of the features noted in relation to the third aspect of the present invention. Further features may also be incorporated in the third aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, the various features discussed above in relation to the first aspect may be utilized by or incorporated into this third aspect as well, individually or in any appropriate combination.
The first block may be directed into the first hole of the receptor layer in any appropriate manner (e.g., using a “pick and place” technology; robotically). More preferably this is done using what may be characterized as fluidic self assembly. In this case the first block is disposed within a fluid that is put into contact with at least the first surface of the receptor layer such that the first block in effect may be carried by the fluid and allowed to “settle” into the first hole of the receptor layer. Stated another way, there may be a flow of sorts at least generally along the first surface of the receptor layer that allows the first block to be positioned within the first hole of the receptor layer. This “flow” may be of the first block through the fluid, or a flow of the fluid with the first block as well. Typically, a plurality of blocks will be disposed in a fluid to form a slurry, and at least the first surface of the receptor layer will be exposed to this slurry. This of course encompasses having the receptor layer be totally submerged in the slurry. At least certain of these blocks and the first hole may be complementarily-shaped—that is, such that the first hole is shaped to accommodate receipt of one of these blocks and typically within a certain orientation within the first hole. It should be appreciated that typically the receptor layer will include a plurality of similarly-shaped first holes, each of which may then receive a single, complimentarily-shaped block in the noted manner.
In one embodiment where there is a zero clearance fit between the first block and the receptor layer when the first block is positioned within the first hole, the first block is positioned within the first hole of the receptor layer before the bonding layer is disposed on the second surface of the receptor layer. Fluidic self assembly could thereby be used to position the first block within the first hole prior to assembling the bonding layer and receptor layer (e.g., the bonding layer could be attached to or formed on the second surface of the receptor layer after fluidic self assembly has been completed). Another option would be for the bonding layer to be disposed on the second surface of the receptor layer prior to positioning the first block within the first hole of the receptor layer. Fluidic self assembly could thereby be used to position the first block within the first hole after the bonding layer has already been formed on or attached to the second surface of the receptor layer. The substrate could include one or more additional layers, including at the time of fluidic self assembly (e.g., a backup layer that “sandwiches” the bonding layer between the backup layer and the receptor layer).
The first block may be the same thickness as or thinner than the receptor layer. In this case, the first surface of the first block initially may be at least substantially coplanar with or recessed relative to the first surface of the receptor layer. Compression of the substrate may thereafter dispose the first surface of the receptor layer in at least substantially coplanar relation with the first surface of the first block. Generally, the bonding material of the bonding layer may “push” the first block within the first hole (in the direction of the first surface of the receptor layer) such that its first surface is at least substantially coplanar with the first surface of the receptor layer. Compression of the substrate may also direct bonding material of the bonding layer into any gap between the receptor layer and the first block. Preferably, any gap between the receptor layer and the first block within the first hole is at least substantially “filled” by bonding material of the bonding layer being forced into this gap by the compression of the substrate. This then provides a substantially planar and continuous surface along which electrical interconnects may extend (and also holds the first block in place). That is, one or more electrical interconnects may extend along the first surface of the receptor layer and onto the first surface of a first block without being unsupported across any gap between an upper edge of the first hole and an upper edge of the first block because of the existence of bonding material in this gap.
In the case where the receptor layer is thicker than the first block, the first hole may be “bigger around” or larger than the first block positioned therein (e.g., there is no zero clearance fit between the receptor layer and the first block in this instance). For instance, the maximum effective size of the first block may be less than the maximum effective size of the first hole at the first surface of the receptor layer. Stated another way, the perimeter of the first hole at the first surface of the receptor layer may be larger than the maximum perimeter of the first block. Therefore, a gap will exist between at least part of the receptor layer and the first block when their respective surfaces are disposed in at least substantially coplanar relation (including having an annular gap between the receptor layer and the first block). Again, preferably this gap is “filled” by bonding material of the bonding layer from the compression of the substrate.
The first block also may be thicker than the receptor layer. In this case the first surface of the receptor layer initially may be recessed relative to the first surface of the first block (e.g., the first block may initially “protrude” beyond the first surface of the receptor layer). Compression of the substrate may thereafter dispose the first surface of the receptor layer in at least substantially coplanar relation with the first surface of the first block. Generally, the first block may be “pressed down” into the bonding layer. This may form a depression within the bonding layer. Compression of the substrate may also direct bonding material of the bonding layer into any gap between the receptor layer and the first block within the first hole. Preferably, any gap between the receptor layer and the first block within the first hole is “filled” by bonding material of the bonding layer being forced into this gap by the compression of the substrate. This then provides a substantially planar and continuous surface along which electrical interconnects may extend. That is, one or more electrical interconnects may extend along the first surface of the receptor layer and onto the first surface of a first block without being unsupported across any gap between an upper edge of the first hole and an upper edge of the first block because of the existence of bonding material in this gap.
In the case where the receptor layer is thinner than the first block, the first hole also may be “bigger around” or larger than the first block positioned therein (e.g., there is no zero clearance fit between the receptor layer and the first lock in this instance). For instance, the maximum effective size of the first block may be less than the maximum effective size of the first hole at the first surface of the receptor layer. Stated another way, the perimeter of the first hole at the first surface of the receptor layer may be larger than the maximum perimeter of the first block. Therefore, a gap may exist between at least part of the receptor layer and the first block when their respective first surfaces are disposed in at least substantially coplanar relation (including having an annular gap between the receptor layer and the first block within the first hole). Again, preferably this gap is “filled” by bonding material of the bonding layer from the compression of the substrate.
In the case where the receptor layer is thinner than the first block, the first hole also may be the same size as or “smaller” than the first block in at least some respect such that there is a zero clearance fit between the perimeter of the first block (at least at its upper edge) and the perimeter of the first hole in the receptor layer (at least at its upper edge). Preferably, no appreciable forces are required to dispose the first block within the first hole in the receptor layer to realize this zero clearance fit, although a press or interference fit relationship could exist between the first block and the receptor layer if warranted. In relation to the noted zero clearance fit, the maximum effective size of the first block may be the same as the maximum effective size of the first hole at the first side of the receptor layer, or the maximum effective size of the first block may be greater than the maximum effective size of the first hole at the first surface of the receptor layer. Stated another way, the perimeter of the first hole at a first surface of the receptor layer may be the same as or smaller than the maximum perimeter of the first block. Therefore, an annular first portion of the first block may be in contact with the receptor layer at least at the intersection of the first hole with the first surface of the receptor layer and prior to the substrate being compressed or after the substrate has been compressed. The result of the subsequent compression of the substrate is subject to a number of characterizations in this situation. One is that the compression may at least slightly deform the receptor layer (e.g., by enlarging at least part of the first hole somewhat). Another is that the compression provides a zero clearance fit between an annular first portion of the first block and a corresponding portion of the sidewall of the receptor layer that defines the first hole. The remainder of the sidewall of the receptor layer may remain spaced from the first block within the first hole that defines the first hole. Again, preferably bonding material of the bonding layer is forced into this gap by the compression of the substrate.
Any appropriate way of placing the substrate in compression may be utilized. It may be desirable to provide a release layer over the receptor layer and the first block prior to placing the substrate in compression. Once the substrate has been compressed, the release layer may be removed. Heat may be applied prior to and/or during the compression as well if desired/required for curing the bonding material of the bonding layer. Any appropriate way of heat treating the bonding material of the bonding layer may be undertaken. One or more materials for the bonding layer may be appropriate and may not require any heat treatment at all. In any case, the bonding material appropriately “fixes” the first block within the first hole of the receptor layer. For at least certain bonding materials, it may be desired to “capture” or sandwich the bonding material between the receptor layer and a backup layer. This backup layer could then be part of the substrate that is compressed in accordance with the foregoing.
Each of the various features discussed in relation to any of the first, second, and third aspects may be used in any of the other aspects of the invention described herein, individually or in any combination.
The present invention will now be described in relation to the accompanying drawings which at least assist in illustrating its various pertinent features. One end of one embodiment of a shaped block is illustrated in
The substrate 30 may be of any size, shape, and/or configuration, and further may be formed from any appropriate material or combination of materials. Once again and as illustrated in
The block 10 includes an upper surface 14 as noted and an oppositely disposed lower surface 16. An annular sidewall 15 extends between the upper surface 14 and lower surface 16, and may be of any appropriate configuration and disposed in any appropriate orientation relative to the surfaces 14, 16. “Annular” means that the sidewall 15 extends a full 360 degrees about a reference axis of the block 10 that extends between the surfaces 14, 16, and by no means limits the configuration of the sidewall 15 to being cylindrical. The intersection of the sidewall 15 with the upper surface 14 defines an upper edge 17.
The block 10 includes at least one electrical contact, bond/bonding pad, or electrical terminal 18 for providing an electrical signal to the block 10 and/or retrieving an electrical signal from the block 10. Typically this electrical terminal 18 will be on the upper surface 14 of the block 10. Any number of terminals 18 may be utilized by the block 10, each terminal 18 may be of any appropriate size, shape, and/or configuration, and each terminal 18 may be disposed at any appropriate location on the block 10. The block 10 further includes at least one electrical component 22. Herein “electrical component 22” means any component that sends or transmits an electrical signal, that receives an electrical signal, or both. Representative electrical components 22 includes without limitation active elements (capable of delivering power to some external device, such as dependent and independent voltage and current sources), passive elements (e.g., resistors, capacitor, inductors), integrated circuits, semiconductor devices, antennas, power sources, electromechanical devices, sensors, transducers, or the like.
Any number of electrical components 22 may be used by a given block 10, and furthermore the electrical components 22 may be disposed in any appropriate arrangement, may be electrically interconnected in any appropriate manner, and may provide any appropriate function or combination of functions. Each electrical component 22 is electrically interconnected (directly or indirectly) with one or more of the terminals 18 in any appropriate manner. Any appropriate number of terminals 18 and electrical components 22 may be used by the block 10, and the various terminals 18 and electrical components 22 may be disposed in any appropriate arrangement. A plurality of the blocks 10 will typically be simultaneously fabricated using an appropriate substrate (not shown)—ultimately to define a plurality of separate blocks 10 for positioning with recesses 38 on the substrate 30.
A preferred approach for positioning blocks 10 within recesses 38 formed on the substrate 30 may be referred to as fluidic self assembly. The fundamental principles of fluidic self assembly are illustrated in
After a desired number of substrate recesses 38 have received a block 10 in accordance with the general technique illustrated in
The above-noted in planarizing layer obviously requires a number of processing steps which of course adds to the overall cost of the fabrication process. These steps include the formation of the planarizing layer, and the formation of vias or holes that extend down through the planarizing layer to the underlying block 10 or other component so as to be able to establish electrical communication therewith. Various embodiments of a multi-layered or composite substrate that each alleviate the need for this planarizing layer, and thereby all related processing steps, are illustrated in FIGS. 3A-C.
The substrate 42 of
The receptor layer 46 of the substrate 42 includes an upper surface 50 and an oppositely disposed lower surface 52. Both the upper surface 50 and the lower surface 52 will typically be at least substantially flat or planar. The receptor layer 46 may be formed from any appropriate material or combination of materials. In one embodiment, the receptor layer 46 is formed from a dielectric material. Representative materials for the receptor layer 46 include without limitation polyimide, polyester, and polyethylene napthalate. The receptor layer 46 also may be flexible, rigid, or otherwise.
A plurality of holes 54 extend from the upper surface 50 to the lower surface 52 of the receptor layer 46, and thereby pass through the entire thickness or vertical extent of the receptor layer 46. An annular sidewall 56 defines a perimeter of each hole 54. The sidewall 56 of each hole 54 may be of any appropriate configuration and disposed in any appropriate orientation relative to the upper surface 50 and lower surface 52 of the receptor layer 46. The intersection of a given sidewall 56 with the upper surface 50 defines an upper edge 60 of the hole 54.
Any number of holes 54 may be used by the receptor layer 46, and the holes 54 may be disposed in any appropriate arrangement. Moreover, the holes 54 may be of appropriate any size, shape, and configuration. In one embodiment, all holes 54 are of the same size, shape, and configuration. In another embodiment, there are at least two different groups of holes 54, where any hole 54 in one group differs in at least some respect from a hole 54 in a different group. In the illustrated embodiment, the sidewall 56 of each hole 54 is perpendicular to the upper surface 50 and lower surface 52 of the receptor layer 46. However and in accordance with the foregoing, the sidewall 56 of each hole 54 could be disposed at a different angle relative to the upper surface 50 and lower surface 52 of the receptor layer 46, such as an inclined orientation as illustrated in relation to the concave recesses 38 in
The holes 54 may be formed through the receptor layer 46 in any appropriate manner. In one embodiment the holes 54 are formed by laser cutting or drilling. Other appropriate techniques- for forming the holes 54 include without limitation punching, electron discharge machining, and water jet cutting. Typically, the bonding layer 64 will be positioned against and secured to the lower surface 52 of the receptor layer 46 after the holes 54 have been formed, although this may not be required in all instances as will be discussed in more detail below in relation to
The bonding layer 64 interfaces with the lower surface 52 of the receptor layer 46, and thereby “closes” one end of each hole 54 of the receptor layer 46. As will be discussed in more detail below, blocks 10 are positioned within the holes 54 through their respective remaining open end at the upper surface 50 of the receptor layer 46. Therefore, the bonding layer 64 may be characterized as being on one side of the receptor layer 46, and the blocks 10 may be characterized as being positioned in the holes 54 from the opposite side of the receptor layer 46.
The bonding material 68 of the bonding layer 64 may be of any appropriate type or composition, and further may be in any appropriate form. For instance, the bonding layer 64 may be a solid, liquid, or paste. When the bonding layer 64 is in the form of a liquid or paste, the bonding layer 64 should be sufficiently viscous. Using a solid (e.g., thermoplastics) as the bonding layer 64 may require a heat treatment to attain a desired degree of viscosity or a softening effect (using heat to soften or “liquify” the bonding layer 64, and such that the bonding layer 64 will return to its solid form when the heat treatment is terminated). Representative materials for the bonding layer 64 include without limitation epoxies, silicone adhesives, pressure-sensitive adhesives, and contact adhesives. A heat treatment of the bonding layer 64 may or may not be required.
The backup layer 74 is optional in at least certain cases. That is, the backup layer 74 may not be required in all instances. The backup layer 74 may be formed from any appropriate material or combination of materials. Furthermore, the backup layer 74 may be flexible, rigid, or otherwise. One function of the backup layer 74 may be to provide structural support for the substrate 42. Other functions may be provided by the backup layer 74 as well. For instance, the backup layer 74 may facilitate incorporating the bonding layer 64 into the structure of the substrate 42. The backup layer 74 may also function to constrain the bonding layer 64 in at least some manner. The backup layer 74 may also facilitate the “seating” of blocks 10 within the bonding layer 64 in a manner that will be discussed in more detail below.
Another embodiment of a multi-layered or composite substrate is illustrated in
Yet another embodiment of a multi-layered or composite substrate is illustrated in
The bonding material 68 for each of the bonding layers 64, 64′ and 64a, 64b may be of any appropriate type as previously noted (e.g., adhesive impregnated carriers, such as cloth, mesh, paper). As will be discussed in more detail below, once blocks 10 are appropriately positioned within the holes 54 through the receptor layer 46, compression is used to dispose the upper surface 14 of each block 10 at least generally coplanar with the upper surface 50 of the receptor layer 46. In addition, bonding material 68 will “flow” into these holes 54 and preferably “fill” any gap between the block 10 within the hole 54 and the sidewall 56 that is disposed about the block 10.
As noted above, the substrates 42, 76, and 88 may be assembled in any appropriate manner.
There are a number of implementations of the composite or multi-layered substrates 42, 76, and 88 in relation to how blocks 10 are integrated therewith to alleviate the need for a planarizing layer. FIGS. 5A-B, 6A-B, and 7A-B are three representative implementations (i.e., others may exist). Each of these “A” figures is a representative pre-compression configuration, while each of these “B” figures is a representative post-compression configuration. Although each of these implementations is illustrated in relation to the substrate 42 of
Preferably, fluidic self assembly is used to dispose blocks 10 in the holes 54 of the substrate 42 for each of the above-noted implementations. However, any other appropriate technique for placing blocks 10 in the holes 54 could be utilized as well (e.g., pick and place). When fluidic self assembly is utilized, at least the receptor layer 46 of the substrate 42 is exposed to the fluid. It may be possible to use fluidic self assembly with just the receptor layer 42 (e.g., the bonding layer 64 could be incorporated after fluidic self assembly has taken place), with the bonding layer 64 already having been mounted to the receptor layer 42 and prior to mounting any backup layer 72, or with the entire substrate 42.
FIGS. 5A-B are directed to a substrate assembly 130. The substrate assembly 130 includes the substrate 42 and at least one block 10a. The block 10a is in accordance with the block 10 of
There are a number of interrelationships of note between the substrate 42 and each of its blocks 10a in relation to the substrate assembly 130 of FIGS. 5A-B. One is that the thickness of the receptor layer 46 (t1) is greater than the thickness of the block 10a (t2). Therefore, at least part of the upper surface 14 of the block 10a may be recessed relative to the upper surface 50 of the receptor layer 46 after the block 10a is initially positioned within the hole 54. The entire lower surface 16 of the block 10a also may be disposed on the bonding layer 64 at this time. It should be appreciated that the upper surface 14 of the block 10a will not necessarily always be parallel to the upper surface 50 of the receptor layer 46 when the block 10a is initially positioned within the hole 54. That is, the block 10a could be “cocked” to a degree at this time (not shown).
Another interrelationship of note is that the block 10a may be disposed within a corresponding hole 54 without establishing a “zero clearance” fit between the block 10a and the receptor layer 46 (e.g., there may be a gap between at least a portion of the perimeter of the block 10a and the receptor layer 46 when the block 10a is disposed within the hole 54). Stated another way, the hole 54 is generally larger in at least some respect than the block 10a positioned therein. “Larger” is subject to a number of characterizations in relation to the illustrated embodiment. One is that the perimeter of each hole 54 at its upper edge 60 is larger any portion of the perimeter of the sidewall 15 of its corresponding block 10a. Another is that the “effective size” of the hole 54 at its upper edge 60 is larger than the maximum “effective size” of the sidewall 15 of the block 10a. Another is that the largest dimension of the hole 54 at its upper edge 60 is greater than the largest dimension of any portion of the sidewall 15 of the block 10a between the upper surface 14 of the block 10a and its lower surface 16. Yet another is that when the upper surface 14 of the block 10a is coplanar with the upper surface 50 of the receptor layer 46 (
The “thickness dimension” of the substrate assembly 130 is compressed after the desired number of holes 54 of the receptor layer 46 have been “filled” with blocks 10a (e.g., compressed between its upper and lower extremes). Compression may be provided in any appropriate manner (e.g., using a pair of opposing planar supports; using a planar support and an opposing roller; using opposing rollers), and the compression pressure may be controlled in any appropriate manner. The entire substrate assembly 130 could be compressed all at once, or different portions could be separately compressed and including at the same or different times. In any case, it may be desirable to include an appropriate release film 134 that extends over the upper surface 50 of the receptor layer 46 and each of its holes 54 prior to compressing the substrate assembly 130. This release film 134 could be removed at any appropriate point after the substrate assembly 130 has been compressed in the desired manner. It may be necessary or at least desirable to heat or control the temperature of the substrate assembly 130 during compression. Any appropriate way of ensuring the release of the substrate assembly 130 from the compressing structure could be utilized (e.g., a release film on the compressing structure, alone or in combination with the release film 134; using an appropriate spray).
Compression of the substrate assembly 130 preferably disposes the upper surface 50 of the receptor layer 46 and the upper surface 14 of the block 10a in at least substantially coplanar relation as illustrated in
After the upper surface 14 of each block 10a has been disposed in at least substantially coplanar relation with the upper surface 50 of the receptor layer 46 (
Finally, preferably any gap between the receptor layer 46 and the block 10a within the hole 54 is occupied by bonding material 68 after the substrate assembly 130 has been compressed. Compare
Some type of heat treatment may be required prior to, during, and/or after the compression has been completed in accordance with the foregoing. Heat treatment may not be required in all instances. In any case, the bonding material 68 will fix the block 10a within the hole 54 (e.g., such that there is no relative movement therebetween). Furthermore, the upper end 69 of the bonding material 68 will provide a suitable surface for supporting any electrical interconnect that extends across this upper end 69 to reach the upper surface 14 of the block 10a.
FIGS. 6A-B are directed to a substrate assembly 142. The substrate assembly 142 includes the substrate 42 and at least one block 10b. The block 10b is in accordance with the block 10 of
There are a number of interrelationships of note between the substrate 42 and each of its blocks 10b in relation to the substrate assembly 142 of FIGS. 6A-B. One is that the thickness of the receptor layer 48 (t1) is less than the thickness of the block 10b (t2). Therefore, at least part of the upper surface 50 of the receptor layer 46 may be recessed from the upper surface 14 of the block 10b. Stated another way, the block 10b may protrude beyond the upper surface 50 of the receptor layer 46 when initially positioned with the hole 54. The entire lower surface 16 of the block 10b also may be disposed on the bonding layer 64 at this time. It should be appreciated that the upper surface 14 of the block 10b will not necessarily always be parallel to the upper surface 50 of the receptor layer 46 when the block 10b is initially positioned within the hole 54. That is, the block 10b could be “cocked” to a degree at this time (not shown).
Another interrelationship of note is that the block 10b may be disposed within a corresponding hole 54 without establishing a zero clearance fit between the block 10b and the receptor layer 46. Stated another way, the hole 54 is generally larger in at least some respect than the block 10b to be positioned therein. “Larger” is subject to a number of characterizations in relation to the illustrated embodiment. One is that the perimeter of each hole 54 at its upper edge 60 is larger than any portion of the perimeter of the sidewall 15 of its corresponding block 10b. Another is that the “effective size” of the hole 54 at its upper edge 60 is larger than the maximum “effective size” of the sidewall 15 of the block 10b. Another is that the largest dimension of the hole 54 at its upper edge 60 is greater than the largest dimension of any portion of the sidewall 15 of the block 10b. Yet another is that when the upper surface 14 of the block 10b is coplanar with the upper surface 50 of the receptor layer 46 (
The “thickness dimension” of the substrate assembly 142 is compressed after the desired number of holes 54 of the receptor layer 46 have been “filled” with blocks 10b (e.g., compressed between its upper and lower extremes). Compression may be provided in any appropriate manner (e.g., using a pair of opposing planar supports; using a planar support and an opposing roller; using opposing rollers), and the compression pressure may be controlled in any appropriate manner. The entire substrate assembly 142 could be compressed all at once, or different portions could be separately compressed and including at the same or different times. In any case, it may be desirable to include an appropriate release film 134 that extends over the upper surface 50 of the receptor layer 46 and each of its holes 54 prior to compressing the substrate assembly 142. This release film 134 could be removed at any appropriate point after the substrate assembly 142 has been compressed in the desired manner. It may be necessary or at least desirable to heat or control the temperature of the substrate assembly 142 during compression. Any appropriate way of ensuring the release of the substrate assembly 142 from the compressing structure could be utilized (e.g., a release film on the compressing structure, alone or in combination with the release film 134; using an appropriate spray).
Compression of the substrate assembly 142 preferably disposes the upper surface 50 of the receptor layer 46 and the upper surface 14 of the block 10b in at least substantially coplanar relation as illustrated in
After the upper surface 14 of each block 10b has been disposed in at least substantially coplanar relation with the upper surface 50 of the receptor layer 46 (
Finally, preferably any gap between the receptor layer 46 and the block 10b within the hole 54 is occupied by bonding material 68 after the substrate assembly 142 has been compressed. Compare
Some type of heat treatment may be required prior to, during, and/or after the compression has been completed in accordance with the foregoing. Heat treatment may not be required in all instances. In any case, the bonding material 68 will fix the block 10b within the hole 54 (e.g., such that there is no relative movement therebetween). Furthermore, the upper end 69 of the bonding material 68 will provide a suitable surface for supporting any electrical interconnect that extends across the upper end 69 to reach the upper surface 14 of the block 10b.
FIGS. 7A-B are directed to a substrate assembly 146. The substrate assembly 146 includes the substrate 42 and at least one block 10c. The block 10c is in accordance with the block 10 of
There are a number of interrelationships of note between the substrate 42 and each of its blocks 10c in relation to the substrate assembly 146 of FIGS. 7A-B. One is that the thickness of the receptor layer 46 (t1) is less than the thickness of the block 1c (t2). Therefore, at least part of the upper surface 50 of the receptor layer 46 may be recessed from the upper surface 14 of the block 10c. Stated another way, the block 10c may protrude beyond the upper surface 50 of the receptor layer 46 when initially positioned with the hole 54. The entire lower surface 16 of the block 10c also may be disposed on the bonding layer 64 at this time. It should be appreciated that the upper surface 14 of the block 10c will not necessarily always be parallel to the upper surface 50 of the receptor layer 46 when the block 10c is initially positioned within the hole 54. That is, the block 10c could be “cocked” to a degree at this time (not shown).
Another interrelationship of note is that the block 10c is disposed within a corresponding hole 54 by establishing a zero clearance fit between the block 10c and the receptor layer 46. Stated another way, the hole 54 is generally smaller in at least some respect than the block 10c to be positioned therein. “Smaller” is subject to a number of characterizations in relation to the illustrated embodiment. One is that the perimeter of each hole 54 at its upper edge 60 is smaller than the perimeter of at least part of the sidewall 15 of its corresponding block 10c. Another is that the “effective size” of the hole 54 at its upper edge 60 is smaller than the maximum “effective size” of the sidewall 15 of the block 10c. Another is that the largest dimension of the hole 54 at its upper edge 60 is smaller than the largest dimension of at least part of the sidewall 15 of the block 10c. Yet another is that when the upper surface 14 of the block 10c is coplanar with the upper surface 50 of the receptor layer 46 (
The “thickness dimension” of the substrate assembly and 46 is compressed after the desired number of holes 54 of the receptor layer 46 have been “filled” with blocks 10c (e.g., compressed between its upper and lower extremes). Compression may be provided in any appropriate manner (e.g., using a pair of opposing planar supports; using a planar support and an opposing roller; using opposing rollers), and the compression pressure may be controlled in any appropriate manner. The entire substrate assembly 146 could be compressed all at once, or different portions could be separately compressed and including at the same or different times. In any case, it may be desirable to include an appropriate release film 134 that extends over the upper surface 50 of the receptor layer 46 and each of its holes 54 prior to compressing the substrate assembly 146. This release film 134 could be removed at any appropriate point after the substrate assembly 146 has been compressed in the desired manner. It may be necessary or at least desirable to heat or control the temperature of the substrate assembly 146 during compression. Any appropriate way of ensuring the release of the substrate assembly 46 from the compressing structure could be utilized (e.g., a release film on the compressing structure, alone or in combination with the release film 134; using an appropriate spray).
Compression of the substrate assembly 146 preferably disposes the upper surface 50 of the receptor layer 46 and the upper surface 14 of the block 10c in at least substantially coplanar relation as illustrated in
Contact between the block 10c and the sidewall 56 of the hole 54 during compression of the substrate assembly 146 also expands at least a portion of the hole 56 to provide the noted zero clearance fit between the block 10c and the receptor layer 46. In the illustrated embodiment, an upper, annular portion of the sidewall 56 associated with the hole 54 may be at least slightly deformed by the compression of the substrate assembly 146 and the resulting engagement between the sidewall 15 of the block 10c and the sidewall 56. When the upper surface 50 of the receptor layer 46 and the upper surface 14 of the block 10c are disposed in coplanar relation, there should not be any gap of any significance between the upper edge 60 of the hole 54 and the upper edge 17 of the block 10c positioned within the hole 54. This provides a suitable surface across which an electrical interconnect may extend and that appropriately supports the electrical interconnect. It should be appreciated that the block 10c and the hole 54 could be the same size and realize a zero clearance fit as well (where disposing the upper surface 50 of the receptor layer 46 at least substantially coplanar with the upper surface 14 of the block 10c does not deform either the receptor layer 46 or the block 10c).
Finally, preferably any gap between the receptor layer 46 and the block 10b within the hole 54 is occupied by bonding material 68 after the substrate assembly 146 has been compressed. Compare
The representative implementations of FIGS. 5A-B, 6A-B, and 7A-B alleviate the need for a planarizing layer and yet provide a desired surface on which one or more electrical interconnects may be disposed. These electrical interconnects may be of any appropriate type, size, shape, and configuration (e.g., a line, a trace).
The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.
This patent application claims priority under 35 U.S.C. §119(e) to U.S. to Provisional Patent Application Ser. No. 60/600,889, that was filed on Aug. 12, 2004, and that is entitled “METHOD OF INTERCONNECTING ELECTRICALLY SELF-ASSEMBLED MICROSTRUCTURES,” as well as to U.S. Provisional Patent Application Ser. No. 60/621,756, that was filed on Oct. 25, 2004, and that is entitled “MULTI-PIECE SUBSTRATE FOR VIALESS INTERCONNECTS.” The entire disclosure of both of these provisional patent applications is hereby incorporated-by reference in their entirety herein.
The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Grant No. DOD/DMEA/90-3-2-0303 by the Department of Defense.
| Number | Date | Country | |
|---|---|---|---|
| 60600889 | Aug 2004 | US | |
| 60621756 | Oct 2004 | US |
