WO2012074563A2

WO2012074563A2 - Ultrasonic assisted filling of cavities

Info

Publication number: WO2012074563A2
Application number: PCT/US2011/021870
Authority: WO
Inventors: Albert P. Perez; Terry Sterrett
Original assignee: Henkel Corporation
Priority date: 2010-01-21
Filing date: 2011-01-20
Publication date: 2012-06-07
Also published as: WO2012074563A3

Abstract

In accordance with the present invention, there are provided highly effective methods for filling cavities in a variety of substrates employing a wide range of filler materials. In accordance with a further embodiment of the present invention, there are provided articles prepared employing invention methods, and novel apparatus which facilitate carrying out invention methods.

Description

LDEI-142

ULTRASONIC ASSISTED FILLING OF CAVITIES

FIELD OF THE INVENTION

[0001] The present invention relates to methods for filling cavities in a substrate, and articles produced thereby, as well as apparatus which facilitate carrying out the invention methods.

BACKGROUND OF THE INVENTION

[0002] In order to achieve void free filling of cavities such as vias, it is desirable to eliminate entrapped air prior to, and during the filling process steps. Material properties related to efficacy of cavity filling include the viscosity of the fill material and the surface tension thereof. Within limits, structure design of the cavity (e.g., open through-hole) and cavity filling process parameters can be adjusted to accommodate material property characteristics. For example, it is common for via structures to be configured as open through-holes so that entrapped air can be displaced through the open bottom via surface as the material is introduced and fills the via. When via fill materials have high process viscosity and/or surface tension, through-hole via fill can be assisted by applying vacuum to the via bottom surface. In this way, via fill material can be directed into via openings in a step-wise manner, whereby material is first printed and then subjected to vacuum (oriented from the via bottom surface), then followed by additional printing/vacuum steps, as needed, until the vias are filled.

[0003] While prior art methods generally provide acceptable means of filling open through-hole vias, they are of limited utility with respect to filling other cavities such as blind via structures because such structures do not have a ready means of evacuating entrapped air during the via filling process. For such structures, filling processes are limited to those employing fill materials having sufficiently low viscosity so as to displace entrapped air as the material fills the cavity structures. This methodology is commonly employed by the printed circuit board industry where molten solder is used to fill blind vias. Beyond this process, there are currently no other readily accessible methodologies for filling cavities such as blind vias in a cost effective way. SUMMARY OF THE INVENTION

[0004] In accordance with the present invention, there are provided highly effective methods for filling cavities in a variety of substrates employing a wide range of filler materials.

[0005] In accordance with a further embodiment of the present invention, there are provided articles prepared employing invention methods, and novel apparatus which facilitate carrying out invention methods.

BRIEF DESCRIPTION OF THE FIGURES

[0006] Figure 1 collectively illustrates prior art methods of filling vias (see Figure 1 A, which illustrates commonly used methodology for copper electrodeposition, and Figure IB, which illustrates commonly used methodology for vacuum assisted printing), and invention ultrasonic assisted methods of filling vias (Figure 1C).

[0007] Figure 2 illustrates an embodiment of the present invention whereby a cavity- containing substrate is subjected to ultrasonic energy in conjunction with multiple applications of a dry via fill paste to produce filled vias.

[0008] Figure 3 illustrates a representative ultrasonic assisted printing process flow for dry via-filled interposer structures.

[0009] Figure 4 illustrates an exemplary apparatus according to the present invention.

[0010] Figure 5 illustrates another exemplary apparatus according to the present invention.

[0011] Figure 6 illustrates yet another exemplary apparatus according to the present invention.

[0012] Figure 7 collectively illustrates exemplary ultrasonic coupling tools suitable for use in the practice of the present invention. Figure 7A illustrates use of an annular clamp plus vacuum to secure the substrate, while Figure 7B illustrates an alternate way to engage substrate employing an annular clamp. [0013] Figure 8 collectively illustrates exemplary ultrasonic assist printing tools suitable for use in the practice of the present invention, using membrane coupling to facilitate transfer of ultrasonic energy from the source to the substrate which is to be filled with Theologically acceptable material. Thus, Figure 8A illustrates use of a fluid-filled membrane to facilitate coupling of ultrasonic energy to the substrate. Figure 8B illustrates an exemplary way in which substrate and fluid-filled membrane can be brought into contact with one another. Figure 8C illustrates an alternate exemplary way in which substrate and fluid-filled membrane can be brought into contact with one another. Figure 8D illustrates an exemplary way in which Theologically acceptable material can be applied to substrate. Figure 8E illustrates the effect of applying ultrasonic energy to the assembly illustrated in Figure 8D. Figures 8F and 8G illustrate the introduction of Theologically acceptable material into the cavities of the substrate as

Theologically acceptable material is applied thereto.

[0014] Figure 9 collectively illustrates exemplary cavity shapes that can be filled in accordance with the present invention. For example, Figure 9A illustrates through vias; Figure 9B illustrates through troughs; Figure 9C illustrates blind vias; Figure 9D illustrates blind troughs; Figure 9E illustrates a bumped surface; and Figure 9F illustrates an undulating surface.

DETAILED DESCRIPTION OF THE INVENTION

[0015] In accordance with the present invention, there are provided methods for creating substantially void-free filled cavities in a substrate having cavities therein, said methods comprising:

applying curable, Theologically acceptable material to said substrate,

subjecting said curable, Theologically acceptable material and/or said substrate to

sufficient ultrasonic energy to facilitate flow of said curable, Theologically acceptable material into said cavities, and

subjecting the curable, Theologically acceptable material to curing conditions. [0016] Optionally, the above-described process can further comprise repeating the steps of: applying curable, Theologically acceptable material to said substrate, and

sufficient ultrasonic energy to facilitate flow of said curable, rheologically acceptable material into said cavities

one or more times prior to subjecting said curable, rheologically acceptable material to curing conditions.

[0017] In accordance with another embodiment of the present invention, there are provided methods for creating substantially void-free filled cavities in a substrate having cavities therein, said methods comprising:

subjecting curable, rheologically acceptable material and/or said substrate, wherein said curable, rheologically acceptable material has been applied to said substrate, to sufficient ultrasonic energy to facilitate flow of said curable, rheologically acceptable material into said cavities, and

subjecting the curable, rheologically acceptable material to curing conditions.

[0018] In accordance with still another embodiment of the present invention, there are provided methods for creating substantially void-free filled cavities in a substrate having cavities therein, said method comprising:

applying optionally curable, rheologically acceptable material to said substrate, and subjecting said optionally curable, rheologically acceptable material and/or said substrate to sufficient ultrasonic energy to facilitate flow of said optionally curable, rheologically acceptable material into said cavities.

[0019] In accordance with still another embodiment of the present invention, there are provided methods for creating substantially void-free filled cavities in a substrate having cavities therein, said methods comprising subjecting said curable, rheologically acceptable material to curing conditions,

wherein said curable, rheologically acceptable material has been applied to said substrate, and wherein the curable, rheologically acceptable material and/or said substrate have thereafter been subjected to sufficient ultrasonic energy to facilitate flow of said curable, rheologically acceptable material into said cavities.

[0020] In accordance with still another embodiment of the present invention, there are provided methods for creating substantially void-free filled cavities in a substrate having cavities therein, said method comprising subjecting optionally curable, rheologically acceptable material and/or said substrate, wherein said optionally curable, rheologically acceptable material has been applied to said substrate, to sufficient ultrasonic energy to facilitate flow of said optionally curable, rheologically acceptable material into said cavities.

[0021] Optionally, any of the above-described processes can further comprise repeating the steps of:

applying curable, rheologically acceptable material to said substrate, and

subjecting said curable, rheologically acceptable material and/or said substrate to

[0022] In accordance with yet another embodiment of the present invention, there are provided articles prepared by any of the methods described herein. Exemplary articles which can be prepared employing invention methods include solder-less 3D package assemblies, 3D package interposers, 3D package-on-package (PoP) assemblies, TSV-3D package integrated package interposers, and the like.

[0023] Articles according to the present invention, comprise a substrate having substantially void-free filled cavities therein, wherein said cavities have an aspect ratio of at least 2:1, with aspect ratios of 3:1, 4:1 or 5:1 being presently preferred.

[0024] As used herein, "substantially void-free cavities" refer to cavities that are at least 50% filled with optionally curable, rheologically acceptable material. In some embodiments, cavities that are at least 60% filled are contemplated; in some embodiments, cavities that are at least 70% filled are contemplated; in some embodiments, cavities that are at least 80% filled are contemplated; in some embodiments, cavities that are at least 90% filled are contemplated; in some embodiments, cavities that are at least 95% filled are contemplated, and the like.

[0025] A wide variety of shapes and sizes of cavities can be filled employing invention methods. Exemplary cavities include blind vias, through vias, blind trenches, through trenches, regular undulations, random undulations, regular-shaped patterns; irregular-shaped patterns, conductive trace patterns, bumped surfaces, or the like. Exemplary cavity shapes are illustrated in Figure 9.

[0026] Cavities contemplated for treatment in accordance with the present invention can also be described in terms of their aspect ratio (i.e., the ratio of depth to diameter, or depth to the x- dimension of the cavity; or depth to the y-dimension of the cavity). Typical aspect ratios contemplated for treatment in accordance with the present invention fall in the range of about 1 : 1 up to about 10:1 ; with aspect ratios in the range of about 2:1 up to about 5:1 being presently preferred.

[0027] As readily recognized by one of skill in the art, a wide variety of substrates can be employed in the practice of the present invention. Exemplary substrates contemplated for use in the practice of the present invention include materials which do not substantially dampen ultrasonic energy applied thereto; suitable substrates can be prepared from a variety of materials, e.g., silicon, glass, ceramic, semiconductor package encapsulant material, plastic (e.g., reinforced plastic), and the like.

[0028] As readily recognized by those of skill in the art, substrates employed herein can be in any of a variety of shapes, e.g., in the form of a honeycomb structure, a printed circuit board, silicon interposers, solder-less 3D package assemblies, 3D package interposers, 3D package-on- package (PoP) assemblies, TSV-3D package integrated package interposers, and the like.

[0029] As recognized by those of skill in the art, a variety of curable, Theologically acceptable materials can be employed in the practice of the present invention. "Curable" materials are those materials which undergo a phase change when subjected to sufficient temperatures for a sufficient amount of time. Typical curing conditions comprise temperatures in the range of about 120°C up to about 190°C for anywhere from a fraction of a minute up to about 60 minutes; or longer.

[0030] "Rheologically acceptable" materials are those which have satisfactory flow properties when applied to a cavity-containing substrate and subjected to invention methods. Curable, rheologically acceptable materials having a wide range of viscosities can be applied employing invention methods. Typically viscosities fall in the range of about 10 - 10 cPs; with viscosities in the range of about 10²— 10⁶ cPs being preferred; and viscosities in the range of about 10³ - 5xl0⁵ cPs being especially preferred.

[0031] Exemplary curable, rheologically acceptable materials contemplated for use in the practice of the present invention include molten metals, solder paste, solder, sinterable powder compositions, in situ precursor nano-particle solutions, pastes, conductive polymers (e.g., polyaniline), and the like. Introduction of molten metals to a substrate surface can be achieved in a variety of ways, e.g., by heating the metal (or solder), e.g., by placing the metal onto a heated substrate surface (e.g., under an inert atmosphere, pouring molten metal from a crucible or similar apparatus onto the substrate surface having a temperature greater than the metal melting point temperature), and thereafter activating the ultrasonic assist printing tool to fill blind vias in the substrate. There are a variety of suitable alternative process for introducing molten metal to a substrate surface, including molten metal jet printing (as taught by Tyndall; see p. 23 of Tyndall Wafer Fab Overview, published by the Tyndall National Institute, Frank Stam, ed., March 2009), molten metal injection molding (as taught by IBM; see, for example, US Pat. No. 5,775,569, see also research.ibm.com/ims/ on the worldwide web), and the like. Such applications of molten metal to substrate would then be followed by ultrasonic assist printing according to the present invention.

[0032] Exemplary curable, rheologically acceptable materials contemplated for use in the practice of the present invention include electrically conductive paste materials comprising polymeric compositions filled with electrically conductive particles such as metal powders, metal-coated powders and graphite. Inherently conductive polymers might also be employed in the present invention. Also contemplated are transient liquid phase sintering (TLPS) materials of the type described in U.S. Pat. No. 5,830,389, incorporated by reference herein in its entirety. [0033] Additional exemplary curable, Theologically acceptable materials contemplated for use herein include conductive inks which include:

(a) a thermally curable resin system comprising

(i) one or more of a maleimide, nadimide, or itaconimide,

(ii) optionally, a comonomer, and

(iii) a catalyst;

(b) a particulated electrically conductive material; and

(c) optionally, an organic solvent.

Other optional ingredients include flow additives, adhesion promoters, rheology modifiers, electrical enhancers, stabilizers, and mixtures of any two or more thereof.

[0034] In some embodiments, conductive inks employed in the practice of the present invention include:

(a) in the range of about 1 to 20 weight percent of the thermally curable resin system, wherein the weight ratio of the one or more of maleimide, nadimide, or

itaconimide/comonomer/catalyst in the resin system falls in the range of about 2-100/4-200/1 ;

(b) in the range of about 40 to 90 weight percent of the particulated electrically conductive material;

(c) in the range of about 0 to 50 weight percent of the organic solvent; and

(d) in the range of about 0 to 10 weight percent of at least one additional component selected from the group consisting of flow additives, adhesion promoters, rheology modifiers, electrical enhancers, stabilizers, and mixtures of any two or more thereof;

wherein weight percent is based on the total of components (a), (b), (c), and (d).

[0035] The one or more maleimide, nadimide, or itaconimide contemplated for use in the practice of the present invention comprise, respectively, the structures I, II, and III:

II III wherein:

m = l-15,

p = 0-15,

each R² is independently selected from hydrogen or lower alkyl, and J is a monovalent or a polyvalent moiety comprising organic or

organosiloxane radicals, and combinations of any two or more thereof.

[0036] In some embodiments, J is a monovalent or polyvalent radical selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, hydrocarbylene, substituted hydrocarbylene, heteroatom-containing hydrocarbylene, substituted heteroatom-containing hydrocarbylene, polysiloxane, polysiloxane-polyurethane block copolymer, and combinations of two or more thereof, optionally containing one or more linkers selected from the group consisting of a covalent bond, -0-, -S-, -NR-, -O-C(O)-, -0-C(0)-0-, -0-C(0)-NR-, -NR-C(O)-, -NR-C(0)-0-, -NR-C(0)-NR-, -S-C(O)-, -S-C(0)-O, -S-C(0)-NR-, -S(O)-, -S(0)₂-, -0-S(0)₂-, -0-S(0)₂-0-, -0-S(0)₂-NR-, -O-S(O)-, -0-S(0)-0-, -0-S(0)-NR-, -O-NR-C(O)-, -0-NR-C(0)-0-,

-0-NR-C(0)-NR-, -NR-O-C(O)-, -NR-0-C(0)-0-, -NR-0-C(0)-NR-, -O-NR-C(S)-,

-0-NR-C(S)-0-, -0-NR-C(S)-NR-, -NR-O-C(S)-, -NR-0-C(S)-0-, -NR-0-C(S)-NR-, -O-C(S)-, -0-C(S)-0-, -0-C(S)-NR-, -NR-C(S)-, -NR-C(S)-0-, -NR-C(S)-NR-, -S-S(0)₂-, -S-S(0)₂-0-, -S-S(0)₂-NR-, -NR-O-S(O)-, -NR-0-S(0)-0-, -NR-0-S(0)-NR-, -NR-0-S(0)₂-,

-NR-0-S(0)₂-0-, -NR-0-S(0)₂-NR-, -O-NR-S(O)-, -0-NR-S(0)-0-, -0-NR-S(0)-NR-, -0-NR-S(0)₂-0-, -0-NR-S(0)₂-NR-, -0-NR-S(0)₂-, -0-P(0)R₂-, -S-P(0)R₂-, -NR-P(0)R₂-, wherein each R is independently hydrogen, alkyl or substituted alkyl, and combinations of any two or more thereof.

[0037] As employed herein, "hydrocarbyl" comprises any organic radical wherein the backbone thereof comprises carbon and hydrogen only. Thus, hydrocarbyl embraces alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, alkylaryl, arylalkyl, arylalkenyl, alkenylaryl, arylalkynyl, alkynylaryl, and the like. [0038] As employed herein, "substituted hydrocarbyl" comprises any of the above-- referenced hydrocarbyl groups further bearing one or more substituents selected from hydroxy, alkoxy (of a lower alkyl group), mercapto (of a lower alkyl group), cycloalkyl, substituted cycloalkyl, heterocyclic, substituted heterocyclic, aryl, substituted aryl, heteroaryl, substituted heteroaryl, aryloxy, substituted aryloxy, halogen, trifluoromethyl, cyano, nitro, nitrone, amino, amido,— C(0)H, acyl, oxyacyl, carboxyl, carbamate, dithiocarbamoyl, sulfonyl, sulfonamide, sulfuryl, and the like.

[0039] As employed herein, "alkyl" refers to saturated straight or branched chain

hydrocarbon radical having in the range of 1 up to about 500 carbon atoms. "Lower alkyl" refers to alkyl groups having in the range of 1 up to about 5 carbon atoms. "Substituted alkyl" refers to alkyl groups further bearing one or more substituents as set forth above.

[0040] As employed herein, "alkenyl" refers to straight or branched chain hydrocarbyl groups having at least one carbon— carbon double bond, and typically having in the range of about 2 up to 500 carbon atoms, and "substituted alkenyl" refers to alkenyl groups further bearing one or more substituents as set forth above.

[0041] As employed herein, "alkynyl" refers to straight or branched chain hydrocarbyl groups having at least one carbon— carbon triple bond, and typically having in the range of about 2 up to 500 carbon atoms, and "substituted alkynyl" refers to alkynyl groups further bearing one or more substituents as set forth above.

[0042] As employed herein, "cycloalkyl" refers to a cyclic ring-containing groups containing in the range of about 3 up to about 50 carbon atoms, and "substituted cycloalkyl" refers to cycloalkyl groups further bearing one or more substituents as set forth above. Cycloalkyl groups include both mono- and polycyclic alkyl groups such as cyclopentyl, cyclohexyl, decalyl, bicycloheptyl, and the like.

[0043] As employed herein, "cycloalkenyl" refers to cyclic ring-containing groups containing in the range of 3 up to 50 carbon atoms and having at least one carbon-carbon double bond, and "substituted cycloalkenyl" refers to cycloalkenyl groups further bearing one or more substituents as set forth above. Cycloalkenyl groups include both mono- and polycyclic alkenyl groups such as cyclopentenyl, cyclopentadienyl, cyclohexenyl, bicycloheptenyl, tricyclodecenyl, and the like.

[0044] As employed herein, "aryl" refers to aromatic groups having in the range of 6 up to 14 carbon atoms and "substituted aryl" refers to aryl groups further bearing one or more substituents as set forth above.

[0045] As employed herein, "alkylaryl" refers to alkyl-substituted aryl groups and

"substituted alkylaryl" refers to alkylaryl groups further bearing one or more substituents as set forth above.

[0046] As employed herein, "arylalkyl" refers to aryl-substituted alkyl groups and

"substituted arylalkyl" refers to arylalkyl groups further bearing one or more substituents as set forth above.

[0047] As employed herein, "arylalkenyl" refers to aryl-substituted alkenyl groups and "substituted arylalkenyl" refers to arylalkenyl groups further bearing one or more substituents as set forth above.

[0048] As employed herein, "alkenylaryl" refers to alkenyl-substituted aryl groups and "substituted alkenylaryl" refers to alkenylaryl groups further bearing one or more substituents as set forth above.

[0049] As employed herein, "arylalkynyl" refers to aryl-substituted alkynyl groups and "substituted arylalkynyl" refers to arylalkynyl groups further bearing one or more substituents as set forth above.

[0050] As employed herein, "alkynylaryl" refers to alkynyl-substituted aryl groups and "substituted alkynylaryl" refers to alkynylaryl groups further bearing one or more substituents as set forth above.

[0051] As employed herein, "heterocyclic" refers to cyclic (i.e., ring-containing) groups containing one or more heteroatoms (e.g., N, O, S, or the like) as part of the ring structure, and having in the range of 3 up to 14 carbon atoms and "substituted heterocyclic" refers to heterocyclic groups further bearing one or more substituents as set forth above. Exemplary heterocyclic moieties include saturated rings, unsaturated rings, and aromatic heteroatom- containing ring systems, e.g., epoxy, tetrahydrofuran, oxazoline, oxazine, pyrrole, pyridine, furan, and the like.

[0052] As employed herein, "hydrocarbylene" refers to divalent straight or branched chain hydrocarbyl groups including alkylene groups, alkenylene groups, alkynylene groups, cycloalkylene groups, heterocycloalkylene groups, arylene groups, heteroarylene groups, alkylarylene groups, arylalkylene groups, arylalkenylene groups, arylalkynylene groups, alkenylarylene groups, alkynylarylene groups, and the like; and "substituted hydrocarbylene" refers to hydrocarbylene groups further bearing one or more substituents as set forth above.

[0053] As employed herein, "alkylene" refers to saturated, divalent straight or branched chain hydrocarbyl groups typically having in the range of about 2 up to about 500 carbon atoms, and "substituted alkylene" refers to alkylene groups further bearing one or more substituents as set forth above.

[0054] As employed herein, "alkenylene" refers to divalent straight or branched chain hydrocarbyl groups having at least one carbon— carbon double bond, and typically having in the range of about 2 up to 500 carbon atoms, and "substituted alkenylene" refers to alkenylene groups further bearing one or more substituents as set forth above.

[0055] As employed herein, "alkynylene" refers to divalent straight or branched chain hydrocarbyl groups having at least one carbon-carbon triple bond, and typically having in the range of about 2 up to 500 carbon atoms, and "substituted alkynylene" refers to alkynylene groups further bearing one or more substituents as set forth above.

[0056] As employed herein, "cycloalkylene" refers to divalent ring-containing groups containing in the range of about 3 up to about 50 carbon atoms, and "substituted cycloalkylene" refers to cycloalkylene groups further bearing one or more substituents as set forth above.

Cycloalkylene groups include both mono- and polycyclic alkylene groups such as

cyclopentylene, cyclohexylene, decalylene, bicycloheptylene, and the like. [0057] As employed herein, "cycloalkenylene" refers to divalent ring-containing groups containing in the range of about 3 up to about 50 carbon atoms and having at least one carbon- carbon double bond, and "substituted cycloalkenylene" refers to cycloalkenylene groups further bearing one or more substituents as set forth above. Cycloalkenylene groups include both mono- and polycyclic alkenylene groups such as cyclopentenylene, cyclopentadienylene,

cyclohexenylene, bicycloheptenylene and the like.

[0058] As employed herein, "heterocycloalkylene" refers to divalent cyclic (i.e., ring- containing) groups containing one or more heteroatoms (e.g., N, O, S, or the like) as part of the ring structure, and having in the range of 3 up to 14 carbon atoms and "substituted

heterocycloalkylene" refers to heterocycloalkylene groups further bearing one or more substituents as set forth above.

[0059] As employed herein, "arylene" refers to divalent aromatic groups typically having in the range of 6 up to 14 carbon atoms and "substituted arylene" refers to arylene groups further bearing one or more substituents as set forth above.

[0060] As employed herein, "alkylarylene" refers to alkyl-substituted divalent aryl groups typically having in the range of about 7 up to 16 carbon atoms and "substituted alkylarylene" refers to alkylarylene groups further bearing one or more substituents as set forth above.

[0061] As employed herein, "arylalkylene" refers to aryl-substituted divalent alkyl groups typically having in the range of about 7 up to 16 carbon atoms and "substituted arylalkylene" refers to arylalkylene groups further bearing one or more substituents as set forth above.

[0062] As employed herein, "arylalkenylene" refers to aryl-substituted divalent alkenyl groups typically having in the range of about 8 up to 16 carbon atoms and "substituted arylalkenylene" refers to arylalkenylene groups further bearing one or more substituents as set forth above.

[0063] As employed herein, "arylalkynylene" refers to aryl-substituted divalent alkynyl groups typically having in the range of about 8 up to 16 carbon atoms and "substituted arylalkynylene" refers to arylalkynylene group further bearing one or more substituents as set forth above. [0064] As employed herein, "alkenylarylene" refers to alkenyl-substituted divalent aryl groups typically having in the range of about 7 up to 16 carbon atoms and "substituted alkenylarylene" refers to alkenylarylene groups further bearing one or more substituents as set forth above.

[0065] As employed herein, "alkynylarylene" refers to alkynyl-substituted divalent aryl groups typically having in the range of about 7 up to 16 carbon atoms and "substituted alkynylarylene" refers to alkynylarylene groups further bearing one or more substituents as set forth above.

[0066] As employed herein, "heteroarylene" refers to divalent aromatic groups containing one or more heteroatoms (e.g., N, O, S or the like) as part of the aromatic ring, and typically having in the range of 3 up to 14 carbon atoms and "substituted heteroarylene" refers to heteroarylene groups further bearing one or more substituents as set forth above.

[0067] As employed herein, "polysiloxane-polyurethane block copolymers" refer to polymers containing both at least one polysiloxane (soft) block and at least one polyurethane (hard) block.

[0068] When one or more of the above described monovalent or polyvalent groups contain one or more of the above described linkers to form the "J" appendage of a maleimide, nadimide or itaconimide group, as readily recognized by those of skill in the art, a wide variety of organic chains can be produced, such as, for example, oxyalkyl, thioalkyl, aminoalkyl, carboxylalkyl, oxyalkenyl, thioalkenyl, aminoalkenyl, carboxyalkenyl, oxyalkynyl, thioalkynyl, aminoalkynyl, carboxyalkynyl, oxycycloalkyl, thiocycloalkyl, aminocycloalkyl, carboxycycloalkyl, oxycloalkenyl, thiocycloalkenyl, aminocycloalkenyl, carboxycycloalkenyl, heterocyclic, oxyheterocyclic, thioheterocyclic, aminoheterocyclic, carboxyheterocyclic, oxyaryl, thioaryl, aminoaryl, carboxyaryl, heteroaryl, oxyheteroaryl, thioheteroaryl, aminoheteroaryl,

carboxyheteroaryl, oxyalkylaryl, thioalkylaryl, aminoalkylaryl, carboxyalkylaryl, oxyarylalkyl, thioarylalkyl, aminoarylalkyl, carboxyarylalkyl, oxyarylalkenyl, thioarylalkenyl,

aminoarylalkenyl, carboxyarylalkenyl, oxyalkenylaryl, thioalkenylaryl, aminoalkenylaryl, carboxyalkenylaryl, oxyarylalkynyl, thioarylalkynyl, aminoarylalkynyl, carboxyarylalkynyl, oxyalkynylaryl, thioalkynylaryl, aminoalkynylaryl or carboxyalkynylaryl. oxyalkylene, thioalkylene, aminoalkylene, carboxyalkylene, oxyalkenylene, thioalkenylene, aminoalkenylene, carboxyalkenylene, oxyalkynylene, thioalkynylene, aminoalkynylene, carboxyalkynylene, oxycycloalkylene, thiocycloalkylene, aminocycloalkylene, carboxycycloalkylene,

oxycycloalkenylene, thiocycloalkenylene, aminocycloalkenylene, carboxycycloalkenylene, oxyarylene, thioarylene, aminoarylene, carboxyarylene, oxyalkylarylene, thioalkylarylene, aminoalkylarylene, carboxyalkylarylene, oxyarylalkylene, thioarylalkylene, aminoarylalkylene, carboxyarylalkylene, oxyarylalkenylene, thioarylalkenylene, aminoarylalkenylene,

carboxyarylalkenylene, oxyalkenylarylene, thioalkenylarylene, aminoalkenylarylene, carboxyalkenylarylene, oxyarylalkynylene, thioarylalkynylene, aminoarylalkynylene, carboxy arylalkynylene, oxyalkynylarylene, thioalkynylarylene, aminoalkynylarylene,

carboxyalkynylarylene, heteroarylene, oxyheteroarylene, thioheteroarylene, aminoheteroarylene, carboxyheteroarylene, heteroatom-containing di- or polyvalent cyclic moiety, oxyheteroatom- containing di- or polyvalent cyclic moiety, thioheteroatom-containing di- or polyvalent cyclic moiety, aminoheteroatom-containing di- or polyvalent cyclic moiety, carboxyheteroatom- containing di- or polyvalent cyclic moiety, and the like.

[0069] In another embodiment, maleimides, nadimides, and itaconimides contemplated for use in the practice of the present invention have the structures I, II, or III wherein:

m = l-6,

p = 0-6, and

J is

(a) saturated straight chain alkyl or branched chain alkyl, optionally containing optionally substituted aryl moieties as substituents on the alkyl chain or as part of the backbone of the alkyl chain, and wherein the alkyl chains have up to about 20 carbon atoms;

(b) a siloxane having the structure: -(C(R³)₂)_d-[Si(R⁴)₂-0]_rSi(R⁴)₂- (C(R³)₂)_e-, -(C(R³)₂)_d-C(R³)-C(0)0-(C(R³)₂

(C(R³)₂)_e-, or -(C(R³)₂^

C(0)0-(C(R³)₂)_e- wherein:

each R is independently hydrogen, alkyl or substituted alkyl, each R⁴ is independently hydrogen, lower alkyl or aryl,

d = 1-10, e = 1-10, and

f = 1-50;

(c) a polyalkylene oxide having the structure:

[(CR₂)_r-0-]r(CR₂)_s- wherein:

each R is independently hydrogen, alkyl or substituted alkyl, r = 1-10,

s = 1-10, and

f is as defined above;

(d) aromatic groups having the structure:

o o

^•II II

Ar-C-O-Z-O-C-Ar- wherein each Ar is a monosubstituted, disubstituted or trisubstituted aromatic or heteroaromatic ring having in the range of 3 up to 10 carbon atoms, and Z is:

(i) saturated straight chain alkylene or branched chain alkylene, optionally containing saturated cyclic moieties as substituents on the alkylene chain or as part of the backbone of the alkylene chain, or

(ii) polyalkylene oxides having the structure:

-[(CR₂)_r-0-]_q-(CR₂)_s- wherein each R is independently defined as above, r and s are each defined as above, and q falls in the range of 1 up to 50;

(e) di- or tri-substituted aromatic moieties having the structure: jj>

-(CR₂)_t-0-C-Ar- C-0-(CR₂)_u|

1,2

wherein each R is independently defined as above, t falls in the range p to 10, u falls in the range of 2 up to 10, and Ar is as defined above; aromatic groups having the structure

0

II

0 (C)o.— (CR₂)_t]_k -Ar— [(C)_0i1 -0- (CR₂)_tl_<

0

Ar- -E— C— N - Ar E N— C II

R R

wherein:

each R is independently defined as above, t = 2-10,

k = 1, 2 or 3,

g = 1 up to about 50,

each Ar is as defined above,

E is -O- or -NR³-, wherein R⁵ is hydrogen or lower alkyl; and

W is

(i) straight or branched chain alkyl, alkylene, oxyalkylene, alkenyl, alkenylene, oxyalkenylene, ester, or polyester,

(ii) a siloxane having the structure -(C(R )₂)d- [Si(R⁴)₂-0]rSi(R⁴)₂-(C(R³)₂)e-, -(C(R³)₂)_d-C(R³)-C(0)0- (C(R³)₂)_d-[Si(R⁴)₂-0]rSi(R⁴)₂-(C(R³)₂)_e-0(0)C-(C(R³)₂)e-, or -(C(R³)₂)_d-C(R³)-0(0)C-(C(R³)₂)_d-[Si(R⁴)₂-0]rSi(R⁴)₂- (C(R³)₂)_e-C(0)0-(C(R³)₂)_e- wherein,

each R³ is independently hydrogen, alkyl or substituted alkyl,

each R⁴ is independently hydrogen, lower alkyl or aryl,

d = 1-10, e = 1-10, and

f = 1-50; or

(iii) a polyalkylene oxide having the structure:

-[(CR₂)_r-0-]r(CR₂)_s- wherein:

each R is independently hydrogen, alkyl or substituted alkyl,

r = 1-10,

s = 1-10, and

f is as defined above;

optionally containing substituents selected from hydroxy, alkoxy, carboxy, nitrile, cycloalkyl or cycloalkenyl;

(g) a urethane group having the structure:

R⁷-U-C(0)-NR⁶-R⁸-NR⁶-C(0)-(0-R⁸-0-C(0)-NR⁶-R⁸-NR⁶-C(0))v-U-R⁸- wherein:

each R⁶ is independently hydrogen or lower alkyl;

each R⁷ is independently an alkyl, aryl, or arylalkyl group having 1 to 18 carbon atoms;

each R is an alkyl or alkyloxy chain having up to about 100 atoms in the chain, optionally substituted with Ar;

U is -0-, -S-, -N(R)-, or -P(L)_!i2- wherein R as defined above, and wherein each L is independently =0, =S, -OR or -R; and v = 0-50;

(h) polycyclic alkenyl; or

(i) mixtures of any two or more thereof.

[0070] In another embodiment, J is of sufficient length to render liquid the one or more maleimide, nadimide, or itaconimide. In some such embodiments, m = 1, 2 or 3, and J is a branched chain alkyl, alkylene or alkylene oxide of sufficient length and branching to render liquid the one or more of maleimide, nadimide, or itaconimide. In still other embodiments of conductive inks of the present invention, J is 10,11 -dioctyl-eicosylene. [0071] Maleimides, nadimides, and itaconimides can be prepared employing techniques well known to those of skill in the art. For example, the most straightforward preparation of maleimides entails formation of the maleamic acid via reaction of the corresponding primary amine with maleic anhydride, followed by dehydrative closure of the maleamic acid with acetic anhydride. Similarly, anhydride precursors of nadimides or itaconimides may be reacted with suitable primary amines. The higher nadimides may be produced by Diels- Alder reactions of the J-substituted maleimide or maleic anhydride with cyclopentadienes and the like.

[0072] Comonomers contemplated for use in the practice of the present invention include (meth)acrylate, epoxy, vinyl ether, vinyl ester, vinyl ketone, vinyl aromatic, vinyl cycloalkyl, allyl amide, and combinations of any two or more thereof. Suitable combinations include but are not limited to (meth)acrylate/vinyl ether and (meth)acrylate/epoxy.

[0073] Exemplary (meth)acrylates contemplated for use in the practice of the present invention may be prepared from a host of different compounds. As used herein, the terms (meth)acrylic and (meth)acrylate are used synonymously with regard to the monomer and monomer-containing component. The terms (meth)acrylic and (meth)acrylate include acrylic, methacrylic, acrylate and methacrylate. The (meth)acrylates may comprise one or more members selected from a monomer including:

(a) the structure represented by the formula:

wherein:

G is hydrogen, halogen, or an alkyl having from 1 to 4 carbon atoms, 1⁰ has from 1 to 16 carbon atoms and is an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, aralkyl, or aryl group, optionally substituted or interrupted with silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbamate, amine, amide, sulfur, sulfonate, or sulfone; urethane acrylates or ureide acrylates represented by the formula:

wherein:

G is hydrogen, halogen, or an alkyl having from 1 to 4 carbon atoms;

R^{1 1} is a divalent alkyl, cycloalkyl, aromatic, or arylalkyl group;

X is -0-, -NH-, or -N(alkyl)-, in which the alkyl radical has from 1 to 8 carbon atoms;

z is 2 to 6; and

R¹² is a z-valent cycloalkyl, aromatic, or arylalkyl group;

(c) a di- or tri-(meth)acrylate selected from polyethylene glycol di(meth)acrylates, bisphenol-A di(meth)acrylates, tetrahydrofuran di(meth)acrylates, hexanediol di(meth)acrylate, trimethylol propane tri(meth)acrylate, and the like, as well as combinations of any two or more thereof; or cyclic acrylates having the structure

wherein

x = 0, 1 ,

G and R¹⁰ are as described above; and

R¹³ is an optionally substituted y-valent cycloalkyl or cycloalkene group having from 5 to 50 carbons, wherein R¹³ is covalently bound in place of any hydrogen on the double bond or R¹⁰, when present, or on the oxygen when R¹⁰ is absent. [0074] Suitable polymerizable (meth)acrylate monomers include cyclic acrylates as described in U.S. Patent Nos. 6,121,358 and 6,322,620, each of which is hereby incorporated by reference in its entirety.

[00 5] Suitable polymerizable (meth)acrylate monomers include triethylene glycol dimethacrylate, tripropylene glycol diacrylate, tetraethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1 ,4-butanediol diacrylate, 1 ,6-hexanediol dimethacrylate, pentaerythritol tetraacrylate, trimethylol propane triacrylate, trimethylol propane trimethacrylate, di- pentaerythritol monohydroxypentaacrylate, pentaerythritol triacrylate, bisphenol-A-ethoxylate dimethacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane propoxylate triacrylate, bisphenol-A-diepoxide dimethacrylate, and the like, as well as combinations of any two or more thereof.

[0076] Additionally, (meth)acrylate monomers contemplated for use herein include polyethylene glycol di(meth)acrylates, bisphenol-A di(meth)acrylates, tetrahydrofuran

(meth)acrylates and di(meth)acrylates, citronellyl acrylate and citronellyl methacrylate, hydroxypropyl (meth)acrylate, hexanediol di(meth)acrylate, trimethylol propane

tri(meth)acrylate, tetrahydrodicyclopentadienyl (meth)acrylate, ethoxylated trimethylol propane triacrylate, triethylene glycol acrylate, triethylene glycol methacrylate, and the like, as well as combinations of any two or more thereof.

[0077] In some embodiments, the comonomer comprises epoxy such as a solid or liquid epoxy resin derived from bisphenol-A and epichlorohydrin. The epoxy resin has an average of 1 to 11 hydroxy 1 groups per molecule plus the terminal epoxy groups. One exemplary resin which may be employed in the conductive ink is an epoxy resin such as Epon 1007 (Shell Corporation).

[0078] Vinyl ethers, ketones, and esters contemplated for use in the practice of the invention include those having the general formula:

wherein:

each Q is independently selected from— O— ,— C(O)— or— C(O)— O— ;

each R is independently selected from hydrogen or lower alkyl; b = 1, 2 or 3; and

J is

C(0)0-(C(R³)₂)_e- wherein:

each R³ is independently hydrogen, alkyl or substituted alkyl, each R⁴ is independently hydrogen, lower alkyl or aryl,

d = 1-10,

e = 1-10, and

f = 1-50;

(c) a poly alky lene oxide having the structure:

wherein:

each R is independently hydrogen, alkyl or substituted alkyl, r = l-10,

s = 1-10, and

f is as defined above;

(d) aromatic groups having the structure:

o o

II II

(ii) polyalkylene oxides having the structure:

(e) di- or tri-substituted aromatic moieties having the structure:

O

?

-(CR₂)_t-0-C-Ar- C-0-(CR₂)_u|

1,2

wherein each R is independently defined as above, t falls in the range of 2 up to 10, u falls in the range of 2 up to 10, and Ar is as defined above; (f) aromatic groups having the structure:

O O II II

(C)_0i1— (CR^ -Ar— [ (C^ - O - tCR^

wherein:

each R is independently defined as above, t = 2-10,

k = 1, 2 or 3,

g = 1 up to about 50,

each Ar is as defined above,

E is -O- or -NR⁵-, wherein R⁵ is hydrogen or lower alkyl; and

W is (i) straight or branched chain alkyl, alkylene, oxyalkylene, alkenyl, alkenylene, oxyalkenylene, ester, or polyester,

(ii) a siloxane having the structure -(C(R )₂)_d- [Si(R⁴)₂-0]r-Si(R⁴)₂-(C(R³)₂)e-, -(C(R³)₂)_d-C(R³)-C(0)0- (C(R³)₂)_d-[Si(R⁴)₂-0]f-Si(R⁴)₂-(C(R³)₂)_e-0(0)C-(C(R³)₂)_e-, or -(C(R³)₂)_d-C(R³)-0(0)C-(C(R³)₂)_d-[Si(R⁴)₂-0]rSi(R⁴)₂- (C(R³)₂)e-C(0)0-(C(R³)₂)_e- wherein,

each R³ is independently hydrogen, alkyl or substituted alkyl,

each R⁴ is independently hydrogen, lower alkyl or aryl,

d = 1-10,

e = 1-10, and

f = 1-50; or

(iii) a poly alkylene oxide having the structure:

-[(CR₂)_r-0-KCR₂)_s- wherein:

each R is independently hydrogen, alkyl or substituted alkyl,

r = 1-10,

s = 1-10, and

f is as defined above;

optionally containing substituents selected from hydroxy, alkoxy, carboxy, nitrile, cycloalkyl or cycloalkenyl; (g) a urethane group having the structure:

each R⁶ is independently hydrogen or lower alkyl;

each R⁷ is independently an alkyl, aryl, or arylalkyl group having 1 to 18 carbon atoms; each R is an alkyl or alkyloxy chain having up to about 100 atoms in the chain, optionally substituted with Ar;

U is -0-, -S-, -N(R)-, or -P(L)_];2- wherein R as defined above, and wherein each L is independently =0, =S, -OR or -R; and v = 0-50;

(h) polycyclic alkenyl; or

0) mixtures of any two or more thereof.

[0079] Exemplary vinyl or polyvinyl compounds embraced by the above generic structure include stearyl vinyl ether, behenyl vinyl ether, eicosyl vinyl ether, isoeicosyl vinyl ether, isotetracosyl vinyl ether, poly(tetrahydrofuran) divinyl ether, tetraethylene glycol divinyl ether, tris-2,4,6-( 1 -vinyloxybutane-4-)oxy- 1 ,3 ,5 -triazine, bis- 1 ,3 -( 1 -vinylozybutane-4-) oxycarbonyl- benzene (alternately referred to as bis(4-vinyloxybutyl)isophthalate; available from Allied-Signal Inc., Morristown, N.J., under the trade name Vectomerd 4010), divinyl ethers prepared by transvinylation between lower vinyl ethers and higher molecular weight di-alcohols (e.g., α,ω- dihydroxy hydrocarbons prepared from dimer acids; an exemplary divinyl ether which can be prepared from such dimer alcohols is 10,1 1-dioctyl eicosane-l,20-divinyl ether, which would likely exist in admixture with other isomeric species produced in ene reactions employed to produce dimer acids), in the presence of a suitable palladium catalyst (see, for example, U.S. Patent No. 6,034,195, herein incorporated by reference in its entirety), optionally hydrogenated α,ω-disubstituted polybutadienes, optionally hydrogenated α,ω-disubstituted polyisoprenes, optionally hydrogenated α,ω-disubstituted poly[(l-ethyl)-l ,2-ethane], and the like. Preferred divinyl resins include stearyl vinyl ether, behenyl vinyl ether, eicosyl vinyl ether, isoeicosyl vinyl ether, poly (tetrahydrofuran) divinyl ether, divinyl ethers prepared by transvinylation between lower vinyl ethers and higher molecular weight di-alcohols (e.g., α,ω-dihydroxy hydrocarbons prepared from dimer acids, as described above; an exemplary divinyl ether which can be prepared from such dimer alcohols is 10,1 1-dioctyl eicosane-l,20-divinyl ether, which would likely exist in admixture with other isomeric species produced in ene reactions employed to produce dimer acids), in the presence of a suitable palladium catalyst (see, for example, U.S. Patent No. 6,034,195, herein incorporated by reference in its entirety), and the like. [0080] Allyl amides suitable for use in the present invention include compounds having the formula

in which

m' is 0 or 1 ;

n' is 1 to 6; and

R¹⁴ is H, an alkyl group having 1 to 18 carbon atoms, an alkyleneoxy group having 1 to 18 carbon atoms, aryl, or substituted aryl having the structure

in which R¹⁵, R¹⁶ and R¹⁷ are independently H or an alkyl or alkyleneoxy group having 1 to 18 carbon atoms;

Ar' is an aromatic group having the following structure:

where A is -0-, -C(O)-, -O-C(O)-, -C(0)-NH-, or -0-C(0)-NH-; and

J is as defined above.

[0081] Exemplary allyl amides include those described in U.S. Patent No. 6,350,841, herein incorporated by reference in its entirety. [0082] Catalysts contemplated for use in the practice of the present invention include free- radical initiators such as peroxides, azo compounds, or combinations of any two or more thereof. Exemplary free-radical initiators include peroxy esters, peroxy carbonates, hydroperoxides, alkylperoxides, arylperoxides, azo compounds, and the like. In some such embodiments, the free radical initiator is dicumyl peroxide, dibenzoyl peroxide, 2-butanone peroxide, fert-butyl perbenzoate, di-tert-butyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, bis(/ert-butyl peroxyisopropyl) benzene, tert-butyl hydroperoxide, or mixture of any two or more thereof. In one embodiment, the catalyst is present in the range of about 0.2 up to about 5 weight percent based on the total weight of the composition.

[0083] The particulated electrically conductive material employed in the practice of the present invention may be selected from silver, copper, silver-coated copper, gold-coated copper, silver-coated aluminum, gold-coated aluminum, coated mica, glass spheres, and the like, as well as mixtures of any two or more thereof.

[0084] Organic solvents, when present, are utilized to substantially dissolve the resin system and to adjust the viscosity of the inks in order to make the ink best suited to form conductive circuitry on substrates with through hole connections. Solvents which may be utilized include hydrocarbons, ethers, alcohols, esters, ketones, and the like, as well as combinations of any two or more thereof. Exemplary solvents include amyl acetate, ethyl 3-ethoxypropionate (EEP, Eastman), diethyl glycol, monoethyl ether, diethylene glycol dimethylene ether, dibasic ester solvent, carbitol, carbitol acetate, butyl carbitol, butyl carbitol acetate, acetone, methyl ethyl ketone, cyclohexanone, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, and the like. In some such embodiments, the solvent is an ester such as amyl acetate.

[0085] Suitable flow additives, adhesion promoters, electrical enhancers, and rheology modifiers and mixtures of any two or more thereof may be added to the compositions of the present invention as desired. Optional flow additives include silicon polymers, ethyl acrylate/2- ethylhexyl aery late copolymers, alkylol ammonium salt of phosphoric acid esters of ketoxime, and the like, as well as combinations of any two or more thereof. Suitable electrical enhancers include polar, ionic, and metal-containing compounds such as hydroquinone, Vitamin E, metallic dryers, metallic acrylates, titanates, phosphoric acid, and other acid catalysts.

[0086] Suitable adhesion promoters include various forms of silane, including

mercaptosilanes and those with a curable functional group. Mercaptosilanes are useful because they provide especially enhanced adhesion on copper substrates. Silanes with curable functional groups include those with a carbon-carbon double bond or an epoxy group, e.g., glycidyl trimethoxysilane (commercially available from OSI under the trade designation A-187). In addition, aminosilanes such as gamma-amino propyl triethoxysilane (commercially available from OSI under the trade designation A-l 100) and trialkoxysilyl isocyanurate derivatives (e.g., Y-l 1597 from OSI) may also be used.

[0087] Suitable rheology modifiers include thermoplastic resins such as polystyrene- polybutadiene copolymer, poly(methyl methacrylate), poly(ethyl methacrylate), and polyvinyl acetal and thixotropes such as THIXATROL compounds. The latter include hydroxy or amine modified aliphatic hydrocarbons such as THIXCIN R, THIXCIN GR, THIXATROL ST and THIXATROL GST, available from Rheox Inc., Hightstown, N.J. These modified aliphatic hydrocarbons are castor oil based materials. The hydroxyl modified aliphatic hydrocarbons are partially dehydrated castor oil or partially dehydrated glycerides of 12-hydroxystearic acid. These hydrocarbons may be further modified with polyamides to form other rheology modifiers such as polyamides of hydroxy stearic acid. Desirably, the hydroxy or amine modified aliphatic hydrocarbon is THIXCIN R.

[0088] Liquid polyester-amide based rheolgical modifiers include THIXATROL TSR, THIXATROL SR and THIXATROL VF, available from Rheox Inc., Hightstown, N.J. These rheological modifiers are described to be reaction products, polycarboxylic acids, polyamines, alkoxylated polyols and capping agents. Useful polycarboxylic acids include sebacic acid, poly(butadiene) dioic acids, dodecane dicarboxylic acids, and the like. Suitable polyamines include diamine alkyls. Capping agents include monocarboxylic acids having aliphatic unsaturation. [0089] Curable, rheologically acceptable material can be applied to the substrate in a variety of ways, e.g., by spin coating, spray coating, flood coating, printing (e.g., screen-printing, stencil-printing, transfer printing, and the like), jetting, squeegee, needle dispensing, and the like. Optionally, to facilitate application of curable, rheologically acceptable material to the substrate, the curable, rheologically acceptable material may be further subjected to a positive pressure so as to enhance the introduction thereof into said cavities. Exemplary supplemental pressures typically fall in the range of about 5-20 Kg/mm².

[0090] Ultrasonic energies contemplated for use in the practice of the present invention can vary widely, typically falling in the range of about 100 - 100,000 Hz for about 10-300 seconds; with energies in the range of about 1,000 - 50,000 Hz being preferred; and energies in the range of about 5,000 - 20,000 Hz being presently most preferred.

[0091] Once cavities are filled, curable, rheologically acceptable material can then be optionally subjected to suitable curing conditions which may comprise temperatures of at least about 80°C but no greater than about 220°C for about 0.5 up to about 60 minutes. Presently preferred temperatures contemplated for use herein fall in the range of about 120°C up to about 190°C. This rapid, short duration heating can be accomplished in a variety of ways, e.g., with an in-line heated rail, a belt furnace, a curing oven, or the like.

[0092] Preferably, temperatures in the range of about 160°C up to about 180°C will be employed, for anywhere from a fraction of a minute up to about 60 minutes; or longer. Such temperatures may be applied directly or in a step- wise fashion, e.g., starting at a room

temperature and ramping up to a temperature of about 40-60°C at a rate of about 5-10°C/minute, which is held for 5-30 minutes, followed by additional elevation of temperature up to about 160°C-180°C at 5-10°C/min. then held at that temperature for a sufficient length of time to facilitate curing of the applied material.

[0093] One of the advantages of the invention methods is that it facilitates preparation of filled cavities while avoiding exposing the substrate or curable, rheologically acceptable material to excessive temperatures, typically accomplishing the desired filling at temperatures no greater than about 260°C. [0094] In accordance with still another embodiment of the present invention, there are provided apparatus' for creating substantially void-free filled cavities in a suitable substrate therefor, said apparatus comprising:

an assembly for securing a substrate optionally having cavities therein,

a source of optionally curable, Theologically acceptable material,

an assembly suitable for applying optionally curable, Theologically acceptable material to said substrate, and

an ultrasonic energy source adapted to be intimately associated with said optionally

curable, Theologically acceptable material and/or said substrate.

[0095] Exemplary assemblies for securing substrate include a weight, a clamp,

vacuum/suction, contact adhesive, and the like (see, for example, Figs. 7 or 8).

[0096] Figure 7, for example, illustrates the use of an annular clamp, and optional vacuum, to assist in holding the substrate in place while optionally curable, Theologically acceptable material is applied thereto.

[0097] Figure 8 illustrates the use of membrane coupling to facilitate transmission of ultrasonic energy from the source thereof to the work-piece being treated with optionally curable, Theologically acceptable material.

[0098] Exemplary sources of optionally curable, Theologically acceptable material include any suitable storage vessel with an exit therefrom, e.g., a syringe, a beaker, a flask, a crucible, and the like.

[0099] Exemplary assemblies suitable for applying optionally curable, Theologically acceptable material to said substrate include squeegee, needle, ink-jet, spray coating, flood coating, and the like.

[00100] Exemplary conditions contemplated for applying optionally curable, Theologically acceptable material to said substrate include use of a squeegee at an angle between about 45-60°, print speed in the range of 10-25 mm/s, with 1-10 printing passes (with 2-7 passes being presently preferred). [00101] Exemplary ultrasonic energy sources adapted to be intimately associated with said optionally curable, rheologically acceptable material and/or said substrate include an ultrasonic transducer, Sonicator XL Ultrasonic Processor (by Misonix Inc.), and the like.

[00102] Optionally, invention apparatus may further comprise an element which facilitates curing of said optionally curable, rheologically acceptable material once introduced into said cavities. Exemplary elements which facilitate said curing include heating elements, irradiation sources, and the like.

[00103] Optionally, invention apparatus may also contain additional element(s) for introduction of cavities into the substrate (e.g., deep reactive ion etching, laser drilling, etc). Exemplary elements for introduction of cavities include mechanical drills, laser irradiation, a source of chemical etchant(s), and the like.

[00104] Exemplary apparatus suitable for carrying out invention methods is illustrated in Figure 4. Substrate 1 (such as a glass plate with cavities therein) is positioned on an assembly for securing same 3 such that the substrate is held firmly in place so that optionally curable, rheologically acceptable material (10) can be applied thereto from the source thereof 5; the substrate and/or assembly for securing same is maintained in intimate contact with an ultrasonic energy source 7, which is then activated to assist in introducing optionally curable, rheologically acceptable material 10 into the cavities in substrate 1 once the optionally curable, rheologically acceptable material is applied to the substrate.

[00105] Another exemplary apparatus suitable for carrying our invention methods is illustrated in Figure 5. Substrate 1 (such as a glass plate) is positioned on an assembly for securing same 3 such that the substrate is held firmly in place. The assembly suitable for applying optionally curable, rheologically acceptable material (10) to said substrate 5 (e.g., a squeegee) is maintained in intimate contact with an ultrasonic energy source 7, which is then activated to assist in introducing optionally curable, rheologically acceptable material into the cavities in the substrate as the optionally curable, rheologically acceptable material is applied to the substrate. [00106] Yet another exemplary apparatus suitable for carrying our invention methods is illustrated in Figure 6. Substrate 1 (such as a glass plate) is positioned on assembly for securing same 3 such that the substrate is held firmly in place. The optionally curable, Theologically acceptable material (10) is maintained in intimate contact with an ultrasonic energy source 7, which is then activated to assist in introducing optionally curable, Theologically acceptable material into the cavities in the substrate as the optionally curable, Theologically acceptable material is applied to the substrate.

[00107] The invention will now be described in greater detail by reference to the following non- limiting examples.

EXAMPLES

Example 1

Printing of Blind VIA without Ultrasonic Assist (Prior Art)

[00108] A substrate was placed onto a printing tool, then a sufficient amount of a Theologically suitable material was applied to the substrate surface so as to substantially completely fill all via openings. Material was then printed into the via openings over 5 printing passes using a polyurethane squeegee having 90 Shore A hardness. The substrate was then removed from the printing tool and analyzed. The cavities were found to be only about 20% filled.

Example 2

Printing of Blind VIA with Direct Ultrasonic Assist

[00109] A substrate was placed onto a printing tool, then directly coupled to an ultrasonic energy source. A sufficient amount of the same rheologically suitable material as employed in Example 1 was applied to the substrate surface so as to substantially completely fill all via openings. 20 KHz of ultrasonic energy was then applied @ 30% maximum energy. Material was then printed into the via openings over 5 printing passes using a polyurethane squeegee having 90 Shore A hardness. Application of ultrasonic energy was continued post-printing for another 60 seconds. The substrate was then removed from the printing tool and analyzed. The cavities were found to be about 95% filled. [00110] Review of these results indicates that ultrasonic assisted filling of vias is substantially more effective then prior art methods.

Example 3

Printing of Blind VIA with Direct Ultrasonic Assist

[00111] As a variation of the protocol described in Example 2, substrate was placed onto a printing tool, then directly coupled to an ultrasonic energy source. A sufficient amount of the same rheologically suitable material as employed in the preceding Examples was applied to the substrate surface so as to substantially completely fill all via openings. 20 KHz of ultrasonic energy was then applied at a suitable energy level so as to decrease the viscosity of the rheologically suitable material, and allow continuous expulsion of air from the rheologically suitable material and the vias. Material was then printed into the via openings over 5 printing passes using a polyurethane squeegee having 90 Shore A hardness. Application of ultrasonic energy at a suitable energy level so as to continue to facilitate expulsion of air from the rheologically suitable material and the vias was continued post-printing for another 60 seconds. The substrate was then removed from the printing tool and analyzed. The cavities were found to be substantially completely (at least 95%) filled.

[00112] Review of these results indicates that ultrasonic assisted filling of vias is substantially more effective then prior art methods.

Example 4

Printing of Blind VIA with Indirect Ultrasonic Assist

[00113] A substrate was placed onto a printing tool, then indirectly coupled to an ultrasonic energy source. A sufficient amount of the same rheologically suitable material as employed in the preceding examples was applied to the substrate surface so as to substantially completely fill all via openings. 20 KHz of ultrasonic energy was then applied @ 30% maximum energy. Material was then printed into the via openings over 5 printing passes using a polyurethane squeegee having 90 Shore A hardness. Application of ultrasonic energy was continued post-printing for another 60 seconds. The substrate was then removed from the printing tool and analyzed. The cavities were found to be about 50% filled. [00114] Review of these results indicates that ultrasonic assisted filling of vias is substantially more effective then prior art methods.

Example 5

Printing of Cavities with low viscosity materials (<50,000 cps)

[00115] A substrate was placed onto a printing tool, then coupled (directly or indirectly) to an ultrasonic energy source. A sufficient amount of a Theologically suitable material (having a viscosity <50,000 cps) was applied to the substrate surface so as to completely fill all via openings. 5 - 20 KHz of ultrasonic energy was then applied @ 30% maximum energy. Material was then printed into the via openings over 5 printing passes using a polyurethane squeegee having 90 Shore A hardness. Application of ultrasonic energy was dis-continued once the desired number of printing passes had been achieved. The substrate was then removed from the printing tool.

Example 6

Printing of Cavities with low viscosity materials (>50,000 to <100,000 cps)

[00116] A substrate was placed onto a printing tool, then coupled (directly or indirectly) to an ultrasonic energy source. A sufficient amount of a rheologically suitable material (having a viscosity >50,000, but <100,000 cps) was applied to the substrate surface so as to completely fill all via openings. 5 - 20 KHz of ultrasonic energy was then applied @ 30% maximum energy. Material was then printed into the via openings over 5 printing passes using a polyurethane squeegee having 90 Shore A hardness. Application of ultrasonic energy was continued post- printing for another 30-120 seconds. The substrate was then removed from the printing tool.

Example 7

Printing of Cavities with high viscosity material (100,000 to 500,000 cps)

[00117] A substrate was placed onto a printing tool, then coupled (directly or indirectly) to an ultrasonic energy source. A sufficient amount of a rheologically suitable material (having a viscosity in the range of about 100,000 to 500,000 cps) was applied to the substrate surface so as to completely fill all via openings. 5 - 20 KHz of ultrasonic energy was then applied @ 30% maximum energy for 30-90 seconds prior to initiation of printing. Material was thereafter printed into the via openings over 5 printing passes using a polyurethane squeegee having 90 Shore A hardness. Application of ultrasonic energy was continued post-printing for another 30-120 seconds. The substrate was then removed from the printing tool.

Example 8

Printing of Cavities with high viscosity material (>500,000 cps)

[00118] A substrate was placed onto a printing tool, then coupled (directly or indirectly) to an ultrasonic energy source. A sufficient amount of a rheologically suitable material (having a viscosity >500,000 cps) was applied to the substrate surface so as to completely fill all via openings. 5 - 20 KHz of ultrasonic energy was then applied @ 30% maximum energy for 1 -3 minutes prior to initiation of printing. Material was thereafter printed into the via openings over 5 printing passes using a polyurethane squeegee having 90 Shore A hardness. Application of ultrasonic energy was continued post-printing for another 1-3 minutes. The substrate was then removed from the printing tool.

[00119] While the exemplary embodiments described herein are presently preferred, it should be understood that these embodiments are offered by way of example only. Other embodiments may include, for example, different techniques for performing the same operations. The invention is not limited to a particular embodiment, but extends to various modifications, combinations, and permutations that nevertheless fall within the scope and spirit of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method for creating substantially void-free filled cavities in a substrate having cavities therein, said method comprising:

applying curable, rheologically acceptable material to said substrate,

sufficient ultrasonic energy to facilitate flow of said curable, rheologically acceptable material into said cavities, and

subjecting the curable, rheologically acceptable material to curing conditions.

2. The method of claim 1 wherein said cavities are blind vias or through vias.

3. The method of claim 1 wherein said cavities are in the shape of blind trenches, through trenches, regular undulations, random undulations, regular-shaped patterns, irregular- shaped patterns, or conductive trace patterns.

4. The method of claim 1 wherein said cavities have an aspect ratio in the range of about 1 :1 up to 10:1 (with 2:1 up to 5:1 being preferred).

5. The method of claim 1 wherein said substrate is prepared from silicon, glass, ceramic, semiconductor package encapsulant material, or plastic.

6. The method of claim 1 wherein said substrate is in the form of a honeycomb structure, silicon interposers, or a printed circuit board.

7. The method of claim 1 wherein said curable, rheologically acceptable material is selected from the group consisting of solder paste, solder, sinterable powder compositions, in situ precursor nano-particle solutions, pastes, and conductive polymers.

8. The method of claim 1 wherein said curable, rheologically acceptable material has a viscosity in the range of 10 - 10⁷ cPs.

9. The method of claim 1 wherein the curable, rheologically acceptable material is applied to the substrate by spin coating, spray coating, flood coating, printing, jetting, or squeegee.

10. The method of claim 1 wherein said curable, rheologically acceptable material is further subjected to a positive pressure so as to enhance the introduction thereof into said cavities.

11. The method of claim 1 wherein said curable, rheologically acceptable material and/or said substrate is subjected to ultrasonic energy in the range of 100 - 100,000 MHz for 10- 300 seconds.

12. The method of claim 1 further comprising repeating the steps of:

applying curable, rheologically acceptable material to said substrate, and

13. The method of claim 1 wherein said method is carried out at a temperature no greater than 260°C.

14. A method for creating substantially void-free filled cavities in a substrate having cavities therein, said method comprising:

subjecting the curable, rheologically acceptable material to curing conditions.

15. A method for creating substantially void-free filled cavities in a substrate having cavities therein, said method comprising:

16. A method for creating substantially void-free filled cavities in a substrate having cavities therein, said method comprising subjecting said curable, rheologically acceptable material to curing conditions,

wherein said curable, rheologically acceptable material has been applied to said substrate, and

wherein the curable, rheologically acceptable material and/or said substrate have

thereafter been subjected to sufficient ultrasonic energy to facilitate flow of said curable, rheologically acceptable material into said cavities.

17. A method for creating substantially void-free filled cavities in a substrate having cavities therein, said method comprising subjecting optionally curable, rheologically acceptable material and/or said substrate, wherein said optionally curable, rheologically acceptable material has been applied to said substrate, to sufficient ultrasonic energy to facilitate flow of said optionally curable, rheologically acceptable material into said cavities.

18. An article produced by the method of any one of claims 1-17.

19. Apparatus for creating substantially void-free filled cavities in a suitable substrate therefor, said apparatus comprising:

an assembly for securing a substrate optionally having cavities therein,

a source of optionally curable, rheologically acceptable material,

an assembly suitable for applying optionally curable, rheologically acceptable material to said substrate, and

curable, rheologically acceptable material and/or said substrate.

20. An article comprising a substrate having substantially void-free filled cavities therein, wherein said cavities have an aspect ratio of at least 2:1.