TWI590732B - Systems and methods of manufacturing printed circuit boards using blind and internal micro vias to couple subassemblies - Google Patents

Description

System and method for manufacturing printed circuit boards using closed and internal micro-perforated coupling sub-assemblies Background of the invention

SUMMARY OF THE INVENTION The present invention is generally directed to printed circuit boards and methods of fabricating the same, and more particularly to printed circuit boards including circuit layers stacked with closed and internal microperforations, and methods of fabricating the same.

Most electronic systems include printed circuit boards with high density electronic interconnects. A printed circuit board (PCB) can include one or more circuit cores, substrates, or carriers. In a fabrication of a printed circuit board having one or more circuit carriers, electronic circuits (such as pads, electronic interconnects, etc.) are fabricated on opposite sides of a separate circuit carrier to form a pair of circuits Floor. These pairs of circuit layers of the board can then be physically or electronically bonded to form a printed circuit board by making an adhesive (or a prepreg or a bond ply) in one In the press, the circuit layer is stacked with the adhesive, the circuit board structure produced by the curing, the through hole is drilled, and then the through hole is plated with a copper material to interconnect the circuit layer pairs.

A curing process is used to cure the adhesive to provide a permanent physical bond to the board structure. However, the adhesive generally shrinks significantly during the curing process. Shrinkage, together with later through hole drilling and plating processes, can cause significant stresses within the structure, resulting in unreliable interconnections or bonds or damage between circuit layers. Accordingly, there is a need for materials and associated processes that can compensate for this shrinkage and that provide a less stress-free and reliable electronic interconnection between pairs of circuit layers.

In addition, plating a via (or perforation) with a copper material requires an additional, expensive, and time consuming process sequence that is difficult to spin quickly. 1 is a flow diagram of a sequential stacking process for fabricating a printed circuit board having stacked vias that includes an expensive and time consuming sequential stacking and plating step. Accordingly, there is a need to provide a printed circuit that can be quickly and easily fabricated and/or ensure that interconnects (or vias or microvias) are aligned on a printed circuit board by reducing the reversal of critical processes, thereby reducing manufacturing time and cost. Board and its manufacturing method.

Summary of invention

Aspects of the present invention are related to and directed to systems and methods for coupling sub-assemblies using closed and internal micro-perforations. An embodiment of the invention provides a method of fabricating a printed circuit comprising attaching a plurality of metal layer carriers to form a first assembly comprising at least one copper foil pad on a first surface, applying a package Sealing the material onto the first surface of the first assembly, curing the encapsulating material and the first assembly; applying a stack of adhesive to one surface of the cured encapsulant to form at least one perforation And curing the encapsulating material to expose at least one copper foil pad, attaching a plurality of metal layer carriers to form a second sub-assembly, and attaching the first sub-assembly to the second sub-assembly.

Another embodiment of the present invention provides a method of fabricating a multilayer printed circuit board comprising forming a first subassembly comprising (a) attaching at least one metal layer carrier to form a first surface a first assembly comprising at least one copper foil pad, (b) applying an encapsulating material to the first surface of the first assembly, (c) curing the encapsulating material and the first assembly, (d) Forming at least a first through hole in the cured encapsulant to expose at least one copper foil pad, (e) forming a conductive pattern on a surface of the cured encapsulant, the conductive pattern including a coupled At least one first perforated conductive pad, (f) applying a stack of adhesive to the surface of the cured encapsulating material, (g) forming at least one hole in the superimposed adhesive adjacent to the at least one first perforation, (h) filling at least one hole with a conductive material to form at least one second perforation, repeating (a) to (e) to form a second sub-assembly, attaching the first assembly and the second assembly The at least one second perforation of the first assembly is aligned approximately to the conductive pad of the second assembly.

Yet another embodiment of the present invention provides an attachment structure for coupling a sub-assembly of a multilayer printed circuit board, the structure including a first assembly, the first assembly including a first metal a layer carrier comprising a first closed via comprising a first pick-up pad positioned in a top surface of the first metal layer carrier, a first stack of adhesive layers positioned along the top a surface and a first pick-up pad, and a first through hole, which is filled with a conductive material and positioned in the first laminated adhesive, the first through hole is in contact with the first pick-up pad, and a second assembly is The second assembly includes a second metal layer carrier including a second closed via including a second pick-up pad positioned in a top surface of the second metal layer carrier, wherein the first assembly utilizes The first superposed adhesive layer is attached to the second assembly such that the first perforation in the first adhesive is approximately aligned with the second dip pad of the second closed perforation.

Simple illustration

1 is a flow chart of a sequential stacking process for fabricating a printed circuit board having stacked vias, including sequential stacking and plating steps; and FIGS. 2a through 2f showing an embodiment in accordance with the present invention. One of the examples utilizes an internal perforation positioned in the encapsulation and adhesive layer to attach the sub-assembly to form a multilayer printed circuit board; Figure 2g is a second to second embodiment of the present invention in accordance with an embodiment of the present invention. a cross-sectional view of the final multilayer printed circuit board; FIG. 3 is a cross-sectional view of a multilayer printed circuit board having three sub-assemblies attached by the processes of FIGS. 2a through 2f, in accordance with an embodiment of the present invention; Figures 4a through 4j illustrate an alternative process for forming a multilayer printed circuit board using an internal microperforated attachment sub-assembly positioned in an adhesive layer in accordance with one embodiment of the present invention; One of the processes according to FIGS. 4a to 4j includes a cross-sectional exploded view of the sub-assembly of the two closed perforations that are coupled by the adhesive and the conductive paste to form a thin perforation to the sub-assembly; FIG. 6 is a perspective view according to the present invention. An embodiment of the method includes coupling an adhesive and a conductive paste to form a wearer A cross-sectional exploded view of another assembly of the stacked perforations on each of the sub-assemblies to the sub-assembly; FIG. 7 is a schematic illustration of the use of a two-machine having an enlarged surface area in accordance with an embodiment of the present invention; A cross-sectional exploded view of another assembly of the conductive paste microperforations between the drilled perforations and the sub-assembly.

Detailed description of the invention

In the following detailed description, specific exemplary embodiments of the invention are shown and described. As will be appreciated by those skilled in the art, the described exemplary embodiments may be modified in various ways without departing from the spirit and scope of the invention. To this end, the drawings and description are to be regarded as exemplary rather than limiting. There may be portions shown in the figures, or portions not shown in the figures, as they are not essential to a complete understanding of the invention and are not discussed in the specification. Similar code numbers represent similar components.

1 is a flow diagram of a sequential stack process for fabricating a printed circuit board having stacked vias, including sequential stacking and plating steps.

2a through 2f illustrate a process for fabricating a printed circuit board in accordance with an embodiment of the present invention comprising attaching a laminated sub-assembly using internal microperforations positioned in an encapsulation and adhesive layer.

In Fig. 2a, the process begins with a superimposed subassembly 100 having four layers and copper pads (e.g., foil) 102 on both sides. The superimposed subassembly 100 further includes two plated or filled through holes 104. The sub-assembly layer can be made of metal, ceramic, or insulating materials (eg, FR4, LCP, Thermomount, Thermount, BT, GPY, such as Teflon, heat transfer carbon (Staboco ( Stablecor)), halogen-free, etc., where GPY is a laminate that is not included in the FR4 category, such as polyimine, ethylene-ethylimine cured epoxy, bismalimide, and other electrical properties. Made of a laminate of grades. However, the invention is not limited thereto. In other embodiments, other suitable substrates and conductive layer materials can be used. In the embodiment illustrated in Figure 2a, the sub-assembly layer has a thickness of from about 3 to 4 mils. However, in other embodiments, the sub-assembly layer and other components may have other suitable dimensions.

In several embodiments, the superposed subassembly 100 can be fabricated using the process described in FIG. In other embodiments, the secondary assembly can be a single stacked secondary assembly having a plurality of single metal layer supports and stacked microperforations. The singularity of a single splicing process for the manufacture of a circuit board is further described in U.S. Patent No. 7, 523, 543, U.S. Provisional Patent Application No. 61/189, 171, and U.S. Patent Application Serial No. 12/772,086. The content is incorporated herein by reference.

In the embodiment illustrated in Figure 2a, the superimposed subassembly 100 comprises four metal layers. In other embodiments, the superposed sub-assembly may include more or less than three metal layer supports. In the embodiment illustrated in Figure 2a, the superimposed sub-assembly comprises two through-hole perforations. In other embodiments, the superposed sub-assembly may have more or less than two perforations. In other embodiments, the through hole perforations may be replaced by stacked microperforations, embedded perforations, and/or closed perforations.

In Figure 2b, the process applies an encapsulating material 106 to a top surface of the laminated subassembly 100 and cures. In several embodiments, the encapsulating material is a dielectric material. In several embodiments, the secondary assembly and the encapsulating material thereon are heated in a preselected temperature range for a preselected temperature to achieve cure.

The encapsulating material can be any suitable uncured insulating material including, but not limited to: FR4, LCP, Thermomount Polyamide, BT, GPY, such as Teflon, heat transfer carbon (Stita Stablecor), halogen-free, etc., wherein GPY is a laminate that is not included in the FR4 category, such as polyimine, ethylene-ethylimine cured epoxy, bismalimide, and A stack of other electrical grades.

In Figure 2c, the process applies a stack of adhesive 108 to the top surface of one of the cured encapsulants 106.

In Fig. 2d, the process drills the overlay adhesive 108 and encapsulation material 106 until a top surface of the copper pad 102 forms a hole 110 for microperforation. Each microperforation may be formed by a laser drilled (and/or mechanically drilled) hole having a diameter of between about 4 and 10 mils. In other embodiments, other suitable techniques for forming a perforated hole can be used. In addition, other perforation sizes can be used.

In Fig. 2e, the hole 110 is filled with a conductive paste, thereby forming microperforations 112. In some embodiments, the microperforation is filled with copper rather than a conductive paste. In one embodiment, the perforated hole is made of a conductive paste when laser is drilled, and copper is used when the hole is mechanically drilled.

In Fig. 2f, a second superposed subassembly 200 having a copper pad 202 on both sides is provided and leads adjacent to the first superimposed subassembly 100.

Figure 2g is a cross-sectional view of the final multilayer printed circuit board of Figures 2a through 2f in accordance with an embodiment of the present invention. In the 2g figure, the first and second sub-assemblies (100, 200) are led and attached. In some applications, it may be difficult to join and fabricate panels with high aspect ratio perforations. Attaching the superimposed sub-assembly using the above process will greatly make the attachment and manufacturing process easier. In the embodiment shown in Fig. 2g, the processes of Figs. 2b to 2e are performed on the top surface of the first superposed subassembly 100. In other embodiments, the processes of Figures 2b through 2e are performed on the top and bottom surfaces of the superposed sub-assembly 100 to allow more than one second sub-assembly 200 to be attached to the first sub-assembly 100.

Figure 3 is a cross-sectional view of a multilayer printed circuit board 300 including three sub-assemblies attached using the processes of Figures 2a through 2f, in accordance with one embodiment of the present invention. In other embodiments, more than three sub-assemblies may be attached using the processes of Figures 2a through 2f. The PCB 300 series includes three sub-assemblies having multiple copper pads 302 and through-holes 304. The secondary assembly is attached by internal micro-perforations 312 embedded in the encapsulation layers (306-1, 306-2) and the adhesive layers (308-1, 308-2). In the embodiment illustrated in Figure 3, the sub-assembly to sub-assembly attachment is performed using a microperforation filled with a conductive paste. In other embodiments, a sub-assembly to sub-assembly attachment may be performed using a solid copper plated microperforated or solid copper via hole perforation.

Figures 4a through 4j illustrate an alternative process for attaching a sub-assembly to form a multilayer printed circuit board using an internal micro-perforation in accordance with an embodiment of the present invention.

In Fig. 4a, the process begins with a superimposed subassembly 400 having four layers and copper pads (e.g., foil) 402 on both sides. The superimposed subassembly 400 further includes two plated or filled closed perforations 404 coupled to the other two plated or filled closed perforations 405. The sub-assembly layer can be made of metal, ceramic, or insulating materials (eg, FR4, LCP, Thermomount, Thermount, BT, GPY, such as Teflon, heat transfer carbon (Staboco ( Stablecor)), halogen-free, etc., where GPY is a laminate that is not included in the FR4 category, such as polyimine, ethylene-ethylimine cured epoxy, bismalimide, and other electrical properties. Made of a laminate of grades. However, the invention is not limited thereto. In other embodiments, other suitable substrates and conductive layer materials can be used. In the embodiment illustrated in Figure 4a, the secondary assembly layer has a thickness of from about 3 to 4 mils. However, in other embodiments, the secondary assembly and other components may have other suitable dimensions.

In several embodiments, the superposed subassembly 400 can be fabricated using the process described in FIG. In other embodiments, the secondary assembly can be a single stacked secondary assembly having a plurality of single metal layer supports and stacked microperforations. A single superposition process for fabricating a circuit board is further described in the patents and patent applications referenced above.

In the embodiment illustrated in Figure 4a, the superimposed subassembly 400 comprises four metal layers. In other embodiments, the superposed sub-assembly may include more or less than three metal layer supports. In the embodiment illustrated in Figure 4a, the superimposed sub-assembly comprises four closed perforations. In other embodiments, the superposed sub-assembly may have more or less than four perforations. In other embodiments, the closed perforations may be replaced by holes, buried perforations, and/or stacked perforations.

In Figure 4b, the process applies an encapsulating material 406 to a top surface of the superposed subassembly 400 and is cured. In several embodiments, the encapsulating material is a dielectric material. In several embodiments, the secondary assembly and the encapsulating material thereon are heated in a preselected temperature range for a preselected temperature to achieve cure.

The encapsulating material can be any suitable uncured insulating material including, but not limited to: FR4, LCP, Thermomount Polyamide, BT, GPY, such as Teflon, heat transfer carbon (Stita Stablecor), halogen-free, etc., wherein GPY is a laminate that is not included in the FR4 category, such as polyimine, ethylene-ethylimine cured epoxy, bismalimide, and A stack of other electrical grades.

In Fig. 4c, the process drills the encapsulation material 406 until a top surface of the copper pad 402 forms a hole 410 for microperforation (or perforation). Each microperforation may be formed by a laser drilled (and/or mechanically drilled) hole having a diameter of between about 4 and 10 mils. In other embodiments, other suitable techniques for forming a perforated hole can be used. In addition, other perforation sizes can be used.

In Fig. 4d, the hole 410 is filled with a conductive paste, thereby forming a closed perforation, for example, a solid copper microperforation 412. In some embodiments, the microperforations 412 are filled with a conductive paste instead of copper. In one embodiment, the perforated hole is made of a conductive paste when laser is drilled, and copper is used when the hole is mechanically drilled.

In Figure 4e, the process is imaging, developing, plating copper, adding a resist. The resist is stripped to form a conductive pattern on the encapsulation layer 406 and on the vias 412. The conductive pattern includes a pick-up pad 414 that is positioned atop the aperture 412.

In Figure 4f, the process applies a layer of superposed adhesive 416 to the cured encapsulant 406 and a top surface of the extraction pad 414.

In Fig. 4g, the process drills the laminated adhesive 416 until a top surface of the extraction pad 414 is formed to form a hole 418 for fine perforation. Each of the fine perforations may be formed by a laser drilled (and/or mechanically drilled) hole having a diameter of between about 1 and 3 mils. In other embodiments, other suitable techniques for forming a perforated hole can be used. In addition, other perforation sizes can be used.

In Figure 4h, the hole 418 is filled with a conductive paste, thereby forming microperforations 420.

In Fig. 4i, a second superposed subassembly 400-2- comprising two closures is formed and aligned on a surface thereof having substantially similar to the first assembly 400 of Fig. 4e. The solid copper microperforation and the conductive pad thereon are such that the micro-perforation of the first superimposed assembly 400 filled with fine conductive paste and the corresponding conductive pad of the second superposed assembly 400-2 are led The combined attachment will be physically and electrically coupled and secured by the laminated adhesive 416.

Figure 4j is a cross-sectional view of the final multilayer printed circuit board of Figures 4a through 4i in accordance with an embodiment of the present invention. In Figure 4j, the first and second sub-assemblies (400, 400-2) are led and attached. In some applications, it may be difficult to join and fabricate panels with high aspect ratio perforations. In some applications, it is too difficult to make complex perforated structures using conventional manufacturing methods. Attaching the superimposed sub-assembly using the above process will greatly make the attachment and manufacturing process easier. In addition, the conductive paste or conductive ink microperforation between the superposed sub-assemblies is very thin (e.g., 3 to 5 mils). Not limited to any particular theory Underneath, fine perforations or joints provide good high frequency conductivity. In several embodiments, the electrical conductivity of the joint is not as good as that of a highly conductive metal such as copper, however, because the joint is thin, it can be used for signals having high frequency characteristics (such as radio frequency signals and the like). Provide conductivity. In addition, the fine copper paste joint can provide minimal disturbance to the current flowing through.

In the embodiment illustrated in Figures 4a through 4j, the process is performed on the top surface of the first superposed subassembly 400. In other embodiments, the process is performed on the top and bottom surfaces of the superposed subassembly 400 to allow more than one second subassembly 400-2 to be attached to the first subassembly 400.

In several embodiments, the conductive paste or conductive ink can comprise a mixture of copper and tin. In other embodiments, other suitable conductive materials can be used for the conductive paste.

Figure 5 is a cross-sectional exploded view of the sub-assembly to sub-assembly attachment 500, the attachment comprising two closed perforations (512-1, 512-2) consisting of an adhesive (not shown) and a conductive paste 520 is coupled to form a fine perforation 420 that conforms to the process of Figures 4a through 4j. The closed perforations (512-1, 512-2) each include a conductive pad (502-1, 502-2) on its outer surface and a conductive pad (514-1, 514-2) on its inner surface. . The conductive paste structure 520 forms a fine perforation in the adhesive (see Figure 4j) which may have the desirable properties discussed above.

6 is another assembly of stacked vias (602, 604) on each of the subassemblies coupled by an adhesive (not shown) and a conductive paste via 606, in accordance with an embodiment of the present invention. A cross-sectional exploded view of the secondary assembly attachment 600. The conductive paste perforations 606 are substantially higher (e.g., z-axis length) compared to the secondary assembly of Figure 5. This higher form of conductive paste perforation is easier to manufacture and Provides good control of the impedance between the layers.

Figure 7 is a diagram showing another assembly of conductive paste microperforations 702 between two mechanically drilled perforations (704, 706) having one enlarged surface area (708, 710) in accordance with an embodiment of the present invention. A cross-sectional exploded view of the assembly attachment 700.

While the above description contains many specific embodiments of the present invention, these embodiments are not to be construed as limiting the scope of the invention For that reason, the scope of the invention should not be determined by the embodiments shown, but by the scope of the claims and their equivalents. For example, although specific components have been shown to be formed of copper, other suitable conductive materials other than copper may be used.

100‧‧‧ superimposed sub-assembly

102,202,302,402‧‧‧ copper pad

104‧‧‧Perforated through hole

106,406‧‧‧Encapsulation material

108,416‧‧‧Overlay adhesive

110,410,418‧‧ holes

112,412,420‧‧‧Microperforation

200,400-2‧‧‧Second superimposed sub-assembly

300‧‧‧Multilayer printed circuit boards

304‧‧‧ hole piercing

306-1, 306-2‧‧‧Encapsulation layer

308-1, 308-2‧‧‧ adhesive layer

312‧‧‧Internal microperforation

400‧‧‧First superimposed sub-assembly

404,405‧‧‧Cleaved or filled closed perforations

414‧‧‧Capture pad

500,600,700‧‧‧ sub-assembly to sub-assembly

502-1, 502-2, 514-1, 514-2‧‧‧ Conductive mat

512-1,512-2‧‧‧closed perforation

520‧‧‧Transfer paste structure

602,604‧‧‧Stacked perforations

606‧‧‧Transfer paste perforation

702‧‧‧Transfer paste microperforation

704,706‧‧‧Mechanical drilling perforation

708,710‧‧‧Amplified surface area

1 is a flow chart of a sequential stacking process for fabricating a printed circuit board having stacked vias, including sequential stacking and plating steps; and FIGS. 2a through 2f showing an embodiment in accordance with the present invention. One of the examples utilizes an internal perforation positioned in the encapsulation and adhesive layer to attach the sub-assembly to form a multilayer printed circuit board; Figure 2g is a second to second embodiment of the present invention in accordance with an embodiment of the present invention. a cross-sectional view of the final multilayer printed circuit board; FIG. 3 is a cross-sectional view of a multilayer printed circuit board having three sub-assemblies attached by the processes of FIGS. 2a through 2f, in accordance with an embodiment of the present invention; Figures 4a through 4j illustrate an alternative process for forming a multilayer printed circuit board using an internal microperforated attachment sub-assembly positioned in an adhesive layer in accordance with one embodiment of the present invention; Figure 5 is a cross-sectional exploded view of the sub-assembly to the sub-assembly of one of the two closed perforations formed by bonding the adhesive and the conductive paste according to the processes of Figures 4a to 4j; Figure 6 Is a cross-sectional exploded view of another assembly to sub-assembly of a stacked perforation on each of the sub-assemblies formed by the adhesive and the conductive paste coupled to the adhesive and the conductive paste, in accordance with an embodiment of the present invention; 7 is a cross-sectional, exploded view of another assembly to subassembly attachment of a conductive paste microperforation between two mechanically drilled perforations having an enlarged surface area, in accordance with an embodiment of the present invention.

100. . . Superimposed subassembly

102. . . Copper pad

104. . . Perforation through the filling hole

106. . . Encapsulation material

108. . . Superimposed adhesive

110. . . hole

112. . . Microperforation

Claims (23)

A method for manufacturing a printed circuit board, comprising: attaching a plurality of metal layer carriers to form a first subassembly, the first assembly comprising at least one copper foil pad on a first surface; applying a Encapsulating material onto the first surface of the first assembly; curing the encapsulating material and the first subassembly; applying a superimposed adhesive to one surface of the cured encapsulating material; forming at least one Perforating in the laminated adhesive and the cured encapsulating material to expose the at least one copper foil pad; attaching a plurality of metal layer carriers to form a second sub-assembly; and attaching the laminated adhesive The first assembly and the second assembly are connected. The method of claim 1, further comprising: attaching a plurality of metal layer carriers to form a third sub-assembly, the third assembly comprising at least one copper foil pad on a first surface; applying one a second encapsulating material to the first surface of the third subassembly; curing the second encapsulating material and the third subassembly; applying a second lamination adhesive to the cured second encapsulation a surface of the material; forming at least one perforation in the second lamination adhesive and the cured second encapsulant to expose at least one copper foil pad of the third assembly; and attaching the third Sub-assembly with the first assembly. The method of claim 1, wherein the at least one perforation is formed The step of exposing the at least one copper foil pad to the laminated adhesive and the cured encapsulant comprises: drilling at least one hole into the laminated adhesive and the cured encapsulating material; The conductive paste fills the at least one hole. The method of claim 3, wherein the conductive paste comprises a material comprising one or more metals. The method of claim 3, wherein the conductive paste comprises a conductive ink. The method of claim 1, wherein the step of attaching the first assembly and the second assembly comprises: aligning the at least one perforation with a conductive pad on the second assembly; The first assembly and the second assembly are attached, wherein the at least one through hole and the conductive pad are electrically coupled. The method of claim 1, wherein the perforation is a microperforation. A method for fabricating a multilayer printed circuit board comprising: forming a first subassembly comprising: (a) attaching at least one metal layer carrier to form a first subassembly, the first subassembly Having at least one copper foil pad on a first surface; (b) applying an encapsulating material to the first surface of the first sub-assembly; (c) curing the encapsulating material and the first sub-assembly; (d) forming at least one first perforation in the cured encapsulating material to expose the at least one copper foil pad; (e) forming a conductive pattern on a surface of the cured encapsulating material, the conductive pattern comprising a conductive pad coupled to the at least one first perforation; (f) applying a superimposed adhesive to the a surface of the cured encapsulating material; (g) forming at least one hole in the superposed adhesive adjacent to the at least one first perforation; (h) filling the at least one hole with a conductive material to form at least one Two perforations; repeating (a) to (e) to form a second sub-assembly; attaching the first sub-assembly to the second sub-assembly, thereby making at least a second of the first sub-assembly The perforations are approximately aligned with at least one copper foil pad of the second subassembly. The method of claim 8, wherein the at least one first perforation of the first assembly is a closed perforation, and wherein the at least one first perforation of the second sub-assembly is a closed perforation. The method of claim 8, wherein the at least one first perforation of the first assembly is electrically coupled to the at least one first perforation of the second subassembly. The method of claim 8, wherein the first perforation is filled with copper. The method of claim 8, wherein the step of forming at least one first perforation in the cured encapsulating material to expose the at least one copper foil pad comprises: Drilling at least one first hole in the cured encapsulating material; and filling the at least one first hole with copper. The method of claim 8, wherein the step of forming the conductive pattern on the surface of the cured encapsulating material comprises: forming a conductive pad on at least a portion of the first perforation. The method of claim 8, wherein the conductive material comprises one or more metals. The method of claim 14, wherein the conductive material comprises a material selected from the group consisting of copper and tin. The method of claim 8, wherein the conductive material comprises a conductive ink. An attachment structure for coupling a plurality of sub-assemblies of a multilayer printed circuit board, the structure comprising: a first assembly, the first assembly comprising a first metal layer carrier comprising: a first closed perforation of the first scooping pad, positioned in a top surface of the first assembly, a first layer of adhesive layer positioned along the top surface and the first crucible Taking a pad, and a first micro-perforation, which is filled with a conductive material and positioned in the first laminated adhesive layer, the first micro-perforation is in contact with the first extraction pad; and a second assembly, The second assembly includes a second metal layer carrier comprising: a second closed perforation comprising a second scooping pad positioned in a top surface of the second assembly, wherein the first assembly is attached to the first superimposed adhesive layer a second assembly, such that the first microperforation in the first laminated adhesive layer is aligned approximately to the second closed perforated second extraction pad The structure of claim 17, wherein the first closed perforation and the second closed perforation comprise copper. The structure of claim 18, wherein the first closed perforation and the second closed perforation are filled with copper. The structure of claim 18, wherein the conductive material comprises one or more metals. The structure of claim 20, wherein the conductive material comprises a material selected from the group consisting of copper and tin. The structure of claim 17, wherein the conductive material comprises a conductive ink. The structure of claim 17, wherein the first microperforation in the first superposed adhesive layer has a thickness of about 3 to 5 mils.