Some content of this application is unavailable at the moment.
If this situation persist, please contact us atFeedback&Contact
1. (WO2019003111) FLEXIBLE CIRCUIT WITH METAL AND METAL OXIDE LAYERS HAVING THE SAME METAL
Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

FLEXIBLE CIRCUIT WITH METAL AND METAL OXIDE LAYERS

HAVING THE SAME METAL

TECHNICAL FIELD

This disclosure relates to flexible composite substrates useful in circuit manufacturing and to methods relates to such substrates.

BACKGROUND

Single or multilayer substrates are used to support electronic circuit components and electrical connections between the electrical components in chip level packaging. Components that generate high power require substrates that are capable of tolerating the heat generated by the high power components. For example, ceramic substrates have been used for chip level packaging of high power components due to their thermal performance and long term reliability.

BRIEF SUMMARY

Some embodiments are directed to a flexible multilayer construction. The flexible construction includes a flexible dielectric metal oxide layer comprising a first metal and having opposing top and bottom major surfaces. At least one electrically conductive via extends through at least a portion of the dielectric metal oxide layer. The electrically conductive via comprises a second metal different from the first metal. An electrically conductive terminal is disposed on the top major surface of the dielectric metal oxide layer. The electrically conductive terminal comprises the first metal and makes electrical and physical contact with the electrically conductive via.

In accordance with some embodiments, a flexible construction includes a flexible electrically continuous first metal layer comprising opposing top and bottom major surfaces. At least one second metal partial via extends from proximate the bottom major surface of the first metal layer partially through a thickness the first metal layer. The bottom surface of the at least one second metal partial via is exposed from the bottom major surface side of the first metal layer. A top surface of the at least one second metal partial via is completely covered by and makes electrical and physical contact with the first metal layer. In a cross-section perpendicular to a plane of the construction, the first metal layer includes a recess on each side of the at least one second metal partial via.

Some embodiments are directed to a method of making a multilayer construction. The method includes providing a flexible electrically conductive layer comprising a first metal and having opposing top and bottom major surfaces. At least one via is formed in the electrically conductive layer. The at least one via extends from the bottom major surface of the electrically conductive layer through only a portion of a thickness of the electrically conductive layer. The at least one via is substantially filled with a second metal that is different from the first metal to form at least one electrically conductive via. A top portion of the electrically conductive layer is patterned so that in a cross-section perpendicular to a plane of the conductive layer, the conductive layer includes a recess on each side of the at least one electrically conductive via. The first metal is converted to an oxide of the first metal in the bottom portion, but not the top portion, of the electrically conductive layer. The conversion of the first metal to an oxide results in an unconverted electrically conductive layer comprising the first metal disposed on a dielectric metal oxide layer comprising an oxide of the first metal.

These and other aspects of the present application will be apparent from the description below. In no event, however, should the above summaries be construed as limitations on the claimed subject matter, which subject matter is defined solely by the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A shows a cross sectional side view of a flexible multilayer construction in which at least a portion of the interface between the electrically conductive terminal and the at least one electrically conductive via is higher than at least one portion of an interface between the electrically conductive terminal and the dielectric metal oxide layer in accordance with some embodiments;

FIG. IB shows a cross sectional side view of a flexible multilayer construction in which at least a portion of the interface between the electrically conductive terminal and the at least one electrically conductive via is lower than at least one portion of an interface between the electrically conductive terminal and the dielectric metal oxide layer in accordance with some embodiments;

FIG. 1C shows a cross sectional side view of a flexible multilayer construction in which at least a portion of the interface between the electrically conductive terminal and the at least one electrically conductive via is at the same level as at least one portion of an interface between the electrically conductive terminal and the dielectric metal oxide layer in accordance with some embodiments;

FIG. 2 shows a cross sectional side view of a flexible construction in accordance with some embodiments; and

FIGS. 3 through 12 are process diagrams illustrating a method of fabricating a multilayer construction in accordance with some embodiments.

The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Substrates that support high power components, such as some light emitting diodes (LEDs), need to be able to tolerate the heat generated by the components. Ceramic substrates have desirable thermal and reliability properties for chip level manufacturing for high power components. However, ceramic substrates in current use are thick and rigid and are not suitable for roll-to-roll manufacturing processes. Embodiments disclosed herein are directed to multilayer flexible constructions that can be useful for high temperature applications and/or employed in roll-to-roll manufacturing processes.

FIGS. 1A through 1C show cross sectional side views of flexible multilayer constructions in accordance with various embodiments. The flexible multilayer construction 100 of FIG. 1A includes a flexible dielectric metal oxide layer 110 that comprises a first metal. For example, the first metal may be aluminum and the flexible dielectric metal oxide layer 110 may be a dielectric aluminum oxide layer. The flexible dielectric metal oxide layer 110 has a top major surface 112 and an opposing bottom major surface 114. According to various embodiments, the maximum thickness of the flexible dielectric metal oxide layer 110 may be less than about 200 microns, or less than about 150 microns, or even less than about 100 microns.

At least one electrically conductive via 140 extends through at least a portion of the dielectric metal oxide layer 110. The electrically conductive via 140 may comprise a second metal 130 that is different than the first metal of the dielectric metal oxide layer 110. For example, the first metal may be aluminum and the second metal may be copper. In some embodiments, the second metal 130 may substantially fill the via 140 that extends through at least a portion of the dielectric metal oxide layer 110. At least one of the electrically conductive vias 140 may be a through via extending at least between the top 112 and bottom 114 major surfaces of the dielectric metal oxide layer 110. In some configurations, a plurality of electrically conductive through vias extend at least between the top 112 and bottom 114 major surfaces of the dielectric metal oxide layer 110.

As depicted in FIG. 1A, in some embodiments, the electrically conductive via 140 forms a protrusion 133 relative to the top surface 112 of the dielectric metal oxide layer 110. The sidewall 141 of the at least one electrically conductive via 140 forms an angle (Θ) with the normal 101 to the plane of the multilayer construction 100. In some embodiments, Θ may be in a range from about zero degrees to about 75 degrees.

An electrically conductive terminal 150 is disposed on the top major surface 112 of the dielectric metal oxide layer 110 and makes electrical and physical contact with the at least one electrically conductive via 140. The electrically conductive terminal 150 comprises the first metal.

First 113 and second 115 recesses may be formed in the top major surface 112 of the flexible dielectric metal oxide layer 110. In some embodiments, the first and second recesses 113, 115 may have different average depths. At least one via 140 may be disposed between the recesses 113, 115. The recesses 113, 115 can align with openings in the electrically conductive terminal 150.

As illustrated in FIGS. 1A through 1C, the interface 132, 132', 132" between the electrically conductive terminal 150 and the electrically conductive via 140 may be at different levels relative to the interface 116, 116', 116" between the electrically conductive terminal 150 and the dielectric metal oxide layer 110.

As shown in FIG. 1A, in some embodiments, at least a portion of the interface 132 between the electrically conductive terminal 150 and the electrically conductive via 140 is higher than at least a portion of an interface 116 between the electrically conductive terminal 150 and the dielectric metal oxide layer 110, as depicted in FIG. 1A.

As shown in FIG. IB, in some embodiments at least a portion of the interface 132' between the electrically conductive terminal 150 and the at least one electrically conductive via 140 is lower than at least a portion of the interface 116' between the electrically conductive terminal 150 and the dielectric metal oxide layer 110.

As shown in FIG. 1C, in some embodiments, at least a portion of the interface 132" between the electrically conductive terminal 150 and the at least one electrically conductive via 140 is at a same level as at least a portion of an interface 116" between the electrically conductive terminal 150 and the dielectric metal oxide layer 110.

FIG. 2 shows a cross sectional side view of a flexible construction 200 in accordance with some embodiments. The flexible construction 200 includes a flexible electrically continuous layer 210 comprising a first metal and having opposing top 212 and bottom 214 major surfaces. The flexible construction 200 includes at least one partial via 240, 250 that comprises a second metal. For example, the first metal of the flexible electrically continuous layer 210 can be a different metal from the second metal used in the via 240, 250. In some embodiments, the first metal is aluminum and the second metal is copper.

The via 240, 250 can extend from proximate the bottom major surface 214 of the first metal layer 210 partially through a thickness the first metal layer 210 such that a bottom surface 242 of the at least one second metal partial via 240 is exposed from the bottom major surface 214 side of the first metal layer 210. A top surface 244 of the at least one second metal partial via 240 can be completely covered by the first metal layer 110. The top surface 244 of the via 240 makes electrical and physical contact with the first metal layer 110. The bottom surface 242 of the at least one second metal partial via 240 may extend beyond the bottom major surface 214 of the first metal layer 210 as shown in FIG. 2.

In a cross-section perpendicular to a plane of the construction 200, the first metal layer 110 includes a recess 216, 218 on each side of the at least one second metal partial via 240. The recesses 216, 218 may have that same or differing widths and/or depths. In some configurations, each recess 216, 218 can be within 1500 microns of the at least one second metal partial via 240, 250. In some embodiments, each recess can be within 1000 microns of the at least one second metal partial via 240, 250.

According to some embodiments, the at least one second metal partial via 240, 250 may have a minimum height H along the thickness direction of the first metal layer 210, and a maximum width W. The ratio of the minimum height to the maximum width, H/W, may be greater than or equal to 1, or H/W may be greater than or equal to 5.

FIGS. 3 through 12 are process diagrams illustrating a method of making a multilayer construction 300 (see FIG. 12) in accordance with some embodiments. The method includes providing a flexible electrically conductive layer 301 comprising a first metal, such as aluminum. The flexible electrically conductive layer 301 has a top major surface 302 and an opposing bottom major surface 303 as depicted in FIG. 3. A resist layer 350 is deposited on the surfaces 302, 303 of the flexible electrically conductive layer 301 (FIG. 4) and the resist layer 350 on the bottom surface 303 is patterned to expose at least one portion of the bottom major surface of the conductive layer as shown in FIG. 5. At least one via is formed in the flexible electrically conductive layer 301. FIG. 6 shows the subassembly after formation of the at least one via 320. The least one via 320 in the electrically conductive layer 301 extends from the bottom major surface 303 of the electrically conductive layer 301 through only a portion of a thickness of the electrically conductive layer 301.

As illustrated in FIG. 7, the at least one via 320 is filled with a second metal 330, different than the first metal, to form at least one electrically conductive via 340. The at least one via 320 can be substantially filled with the second metal using one or more of electroplating and electroless deposition, for example, to form the electrically conductive via 340. The resist layer 350 on the top surface 302 of the electrically conductive layer 301 is patterned (FIG. 8) and the top portion 305 of the electrically conductive layer 301 is patterned according to the pattern of the resist 350 (FIG. 9). As shown in FIG. 9, after patterning the top portion 305, in a cross-section perpendicular to a plane of the conductive layer 301, the conductive layer 301 includes a recess 311, 312 on each side of the at least one electrically conductive via 340. A resist layer 360 is disposed over the top surface 302 of the electrically conductive layer 301, e.g., by lamination (FIG. 10). The first metal is converted to an oxide of the first metal in the bottom 304 portion, but not the top 305 portion, of the electrically conductive layer 301, as shown in FIG. 11. The first metal may be converted to the oxide of the first metal by electrolytic oxidation, for example. Conversion of the first metal to an oxide of the first metal results in an unconverted electrically conductive layer 332 comprising the first metal disposed on a dielectric metal oxide layer 331 comprising an oxide of the first metal. FIG. 12 illustrates the multilayer construction 300 after the resist layer 360 has been removed.

Items discussed in this disclosure include the following items:

Item 1. A flexible multilayer construction, comprising:

a flexible dielectric metal oxide layer comprising a first metal and opposing top and bottom major surfaces;

at least one electrically conductive via extending through at least a portion of the dielectric metal oxide layer and comprising a second metal different than the first metal; and

an electrically conductive terminal disposed on the top major surface of the dielectric metal oxide layer and making electrical and physical contact with the at least one electrically conductive via and comprising the first metal.

Item 2. The flexible multilayer construction of item 1, wherein the first metal is aluminum, the dielectric metal oxide layer is a dielectric aluminum oxide layer, and the second metal is copper.

Item 3. The flexible multilayer construction of any of items 1 through 2, wherein each electrically conductive via in the at least one electrically conductive via comprises a via extending through the at least a portion of the dielectric metal oxide layer and the second metal substantially filling the via.

Item 4. The flexible multilayer construction of any of items 1 through 3, wherein at least one electrically conductive via in the at least one electrically conductive via is a through via extending at least between the top and bottom major surfaces of the dielectric metal oxide layer.

Item 5. The flexible multilayer construction of any of items 1 through 4, wherein a maximum thickness of the flexible dielectric metal oxide layer is less than about 200 microns.

Item 6. The flexible multilayer construction of any of items 1 through 4, wherein a maximum thickness of the flexible dielectric metal oxide layer is less than about 150 microns.

Item 7. The flexible multilayer construction of any of items 1 through 4, wherein a maximum thickness of the flexible dielectric metal oxide layer is less than about 100 microns.

Item 8. The flexible multilayer construction of any of items 1 through 7, wherein at least a portion of an interface between the electrically conductive terminal and the at least one electrically conductive via is higher than at least a portion of an interface between the electrically conductive terminal and the dielectric metal oxide layer.

Item 9. The flexible multilayer construction of any of items 1 through 7, wherein at least a portion of an interface between the electrically conductive terminal and the at least one electrically conductive via is lower than at least a portion of an interface between the electrically conductive terminal and the dielectric metal oxide layer.

Item 10. The flexible multilayer construction of any of items 1 through 7, wherein at least a portion of an interface between the electrically conductive terminal and the at least one electrically conductive via is at a same level as at least a portion of an interface between the electrically conductive terminal and the dielectric metal oxide layer.

Item 11. The flexible multilayer construction of any of items 1 through 10, wherein the at least one electrically conductive via comprises a plurality of electrically conductive through vias, each electrically conductive through via extending at least between the top and bottom major surfaces of the dielectric metal oxide layer.

Item 12. The flexible multilayer construction of any of items 1 through 11, wherein the at least one electrically conductive via forms a protrusion relative to the top surface of the dielectric metal oxide layer.

Item 13. The flexible multilayer construction of any of items 1 through 12, wherein a sidewall of the at least one electrically conductive via forms an angle (Θ) with a normal to a plane of the multilayer construction in a range from about zero to about 75 degrees.

Item 14. The flexible multilayer construction of any of items 1 through 13, wherein the flexible dielectric metal oxide layer defines first and second recesses formed in the top major surface thereof, the first and second recesses having different average depths.

Item 15. A flexible construction, comprising:

a flexible electrically continuous first metal layer comprising opposing top and bottom major surfaces; and

at least one second metal partial via extending from proximate the bottom major surface of the first metal layer partially through a thickness the first metal layer such that a bottom surface of the at least one second metal partial via is exposed from the bottom major surface side of the first metal layer and a top surface of the at least one second metal partial via is completely covered by and makes electrical and physical contact with the first metal layer, wherein in a cross-section perpendicular to a plane of the construction, the first metal layer includes a recess on each side of the at least one second metal partial via.

Item 16. The flexible construction of item 15, wherein the first metal is aluminum and the second metal is copper.

Item 17. The flexible construction of any of items 15 through 16, wherein the at least one second metal partial via comprises a minimum height H along the thickness direction of the first metal layer, and a maximum width W, H/W > 1.

Item 18. The flexible construction of any of items 15 through 16, wherein the at least one second metal partial via comprises a minimum height H along the thickness direction of the first metal layer, and a maximum width W, H/W > 5.

Item 19. The flexible construction of any of items 15 through 18, wherein each recess is within

1500 microns of the at least one second metal partial via.

Item 20. The flexible construction of any of items 15 through 18, wherein each recess is within

1000 microns of the at least one second metal partial via.

Item 21. The flexible construction of any of items 15 through 20, wherein the bottom surface of the at least one second metal partial via extends beyond the bottom major surface of the first metal layer.

Item 22. A method of making a multilayer construction, comprising the steps of:

providing a flexible electrically conductive layer comprising a first metal and opposing top and bottom major surfaces;

forming at least one via in the electrically conductive layer extending from the bottom major surface of the electrically conductive layer through only a portion of a thickness of the electrically conductive layer;

substantially filling the at least one via with a second metal different than the first metal to form at least one electrically conductive via;

patterning a top portion of the electrically conductive layer so that in a cross-section perpendicular to a plane of the conductive layer, the conductive layer includes a recess on each side of the at least one electrically conductive via; and

converting the first metal to an oxide of the first metal in a bottom, but not the top, portion of the electrically conductive layer, resulting in an unconverted electrically conductive layer comprising the first metal disposed on a dielectric metal oxide layer comprising an oxide of the first metal.

Item 23. The method of item 22, wherein the step of forming the at least one via comprises first coating the bottom major surface of the conductive layer with a first resist layer followed by patterning the first resist layer to expose at least one portion of the bottom major surface of the conductive layer.

Item 24. The method of any of items 22 through 23, wherein the at least one via is substantially filled with the second metal using one or more of electroplating and electroless deposition.

Item 25. The method of any of items 22 through 24, wherein the first metal is converted to the oxide of the first metal by electrolytic oxidation.

Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. The use of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.

Various modifications and alterations of the embodiments will be apparent to those skilled in the art and it should be understood that this scope of this disclosure is not limited to the illustrative embodiments set forth herein. For example, the reader should assume that features of one disclosed embodiment can also be applied to all other disclosed embodiments unless otherwise indicated.