WO2024158604A2

WO2024158604A2 - Optically efficient led die attach

Info

Publication number: WO2024158604A2
Application number: PCT/US2024/011922
Authority: WO
Inventors: Michael J. Renn; Kurt K. Christenson; Matthew Connor SCHRANDT
Original assignee: Optomec, Inc.
Priority date: 2023-01-23
Filing date: 2024-01-18
Publication date: 2024-08-02

Abstract

Methods for making electrical connections to obscured contacts on an electronic component, such as when an LED die is placed active side down on a transparent substrate, and devices manufactured therefrom. In some examples a conductive material, optionally with an underlying dielectric or insulating layer, is deposited on the component that wraps from the contact around to a component face which will not be obscured. After the face with the contact is placed on the substrate, connection can be made to the conductive material on the unobscured face. In other examples a contact can be disposed on a conductive bump on the substrate. Conductive traces on the substrate are shaped to prevent shorting between contacts. The faces of the die can be coated with a reflective material to increase the LED output in a desired direction, for example through the substrate.

Description

OPTICALLY EFFICIENT LED DIE ATTACH

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of the filing of U.S. Provisional Patent Application No. 63/440,628, entitled “OPTICALLY EFFICIENT LED DIE ATTACH”, filed on January 23, 2024, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] Note that the following discussion may refer to a number of publications and references. Discussion of such publications herein is given for more complete background of the scientific principles and is not to be construed as an admission that such publications or references, or those submitted in any invention disclosure statement submitted for this patent application, are prior art for patentability determination purposes or are relevant to the present invention, per 37 C.F.R. § 1.97(h).

[0003] Light emitting diodes (LEDs) have long been available in prepackaged assemblies that were then attached to Printed Circuit Boards (PCBs) or other driving circuitry. LED die are made en masse on semiconductor and sapphire wafers in a semiconductor fabrication process with optically-active layers that create and emit light deposited to form the active surface of the wafers. Electrical contacts are typically fabricated on the active surface, with one of the contacts optionally routed to the backside surface of the wafer with the driving current passing thru a conductive wafer substrate. The wafers are then diced or singulated to create the individual die. LED die size range in area from several square millimeters for bright, high-power devices to tiny devices much less than 1 mm².

[0004] LED die require two electrical connections that act as a source and sink for the driving current to the active surface of the device. The active surface is normally mounted facing upward, away from the substrate, and the majority of the light is desirably emitted upward. Light can pass downward through the device, but that light is absorbed by the bulk semiconductor substrate. In the case of sapphire substrates, a reflective layer is often applied to the backside surface to reflect the light back toward the active surface. As fabricated, the contacts for the electrical connections can both be on the active surface or they can be on opposite sides of the die. Contacts on the bottom surface are typically opaque and substantially reflective. LEDs are typically mounted with the active surface oriented upward, away from the substrate, often with external reflecting surfaces to guide any light that leaks out the sidewalls in the desired direction. Most currently manufactured LED die are intended to emit light away from the substrate and are not well suited to emit light into the substrate.

[0005] An LED die package requires several features to operate, including:

• The die must be mechanically fixed to some platform or substrate. • It must have at least two electrical connections to act as the source and sink of the operating current. Connections to the active surface of the die have historically been formed by wire bond techniques. The substrate acts as one of the electrical contacts if the die was created with a contact on the bottom surface.

• Thermal management is required to dissipate heat generated during light generation that can damage the device. The die is typically mounted with thermally conductive adhesive to enable heat to flow from the die to the substrate.

• Light emerges from each transparent surface in an approximately Lambertian distribution. Light from the active surface is aimed on average upward. A smaller fraction of the light is emitted from the sidewall surfaces. Light from these surfaces can be redirected upward by mounting the die on a reflective concave surface, for example a flat-bottomed bowl with 45-degree sloped sides. The directional distribution of the combined top and side-radiated light can be shaped by a lens placed above the die.

• For some applications the assembly is encapsulated in epoxy which serves to protect the die and to direct the light emission.

[0006] FIGS. 1-3 show typical die packaging configurations. FIG. 1 shows a common cylindrical package with radial leads and a round top that forms a lens, which comprises a typical prepackaged LED die 11 that is mounted in reflecting cup 12 that also acts as the electrical connection to the backside surface of the die from electrical lead 14. The second contact from electrical lead 18 is made by wire bond 13. Encapsulant 15 is molded into lens shape 17 to direct light 16 in the desired direction. The lens of this convenient, low-cost package enables focusing of the light 16, but the design has poor thermal characteristics, extends upward substantially from the substrate, and does not easily scale downward in size.

[0007] FIGS. 2A-2B are top and side views, respectively, of a typical bare LED die in a surface-mount package with a lower vertical profile and better thermal characteristics than the package of FIG. 1 and that is typically used for mid-range power devices. The die has electrical n- contact 21 on the active surface and p-contact 22 on the backside surface. The electrically conductive bulk of the device is surrounded by side wall faces 28. Light 26 is typically emitted from thin active regions 24 on the active surface except for n-contact 21.

[0008] FIG. 3 shows a typical Chip on Board (COB) configuration often used for higher power devices where p-contact 32 of the LED die 39 is attached directly to positive current source trace 33 present on the substrate 29. Substrate 29 is typically thermally conductive, comprising, for example, aluminum nitride, and efficiently diffuses the heat before it is conducted into a larger heatsink structure. The second electrical contact is formed by wire bond 35 running from negative trace 30 to the LED’s n-contact 31. Light 36 is emitted upward from one or more active regions 34 that surround n-contact 31. Active regions 34 also emit light downward into the bulk of the device. This light can reflect off backside p-contact 32 or sidewalls 38 of the device and eventually emerge from the top of the device. Light in the bulk of the device can alternatively be absorbed or it can emerge as emitted light 37 from sidewalls 38. In the case of semiconductor substrates, p-contact layer 32 and positive trace 33 are typically opaque, so little light passes down into the substrate.

[0009] FIG. 4 shows a more recent COB mounting technique based on Aerosol Jet® microprinting technology. Electric current is provided by a metal line printed from the substrate to a contact on the die. One or both electrical connections can be printed. P-contact 42 of die 49 is attached directly to positive current source trace 43 present on bulk substrate 44. The second electrical connection is formed between negative current sink trace 40 and the LED’s n-contact 41 by printed interconnect 45. Electrically insulating dielectric 47 is printed before the connection as needed to prevent shorting.

[0010] Miniaturization and cost reduction have driven the use of an unpackaged “bare” LED die mounted directly onto a substrate. Most currently manufactured LED die are intended to emit light away from the substrate and are not well suited to emit light into the substrate. Emission into the substrate may be desired, for instance, when the LED is mounted on the side of a transparent substrate away from the desired illuminated region to protect the LED or ease fabrication of the overall product. This variation on the Chip-on-Board approach requires that the mounting process include electrical connection and any steps needed to direct the light in the desired direction. This is particularly challenging when the light should be directed down through the substrate, as when the LED is mounted on the inside surface (side away from the viewer) of a transparent substrate. In this case, an LED die designed to emit upward around the electrical contact on the active surface is inverted, placing the electrical contact on the bottom surface adjacent to and obscured by the substrate.

SUMMARY OF THE INVENTION

[0011] An embodiment of the present invention is a method of electrically contacting an electronic component, the method comprising depositing a first conductive material on the electronic component, the first conductive material contacting a first contact on a first surface of the electronic component and extending to a second surface adjacent to the first surface; mounting the first surface against a substrate; and electrically connecting the first conductive material on the second surface to a first conductive trace on the substrate. The method preferably further comprises depositing a dielectric or insulating material prior to depositing the conductive material and subsequently depositing the conductive material on the dielectric or insulating material, the dielectric or insulating material extending from the first contact to the second surface. The method preferably further comprises electrically connecting a second contact of the electronic component to a second conductive trace on the substrate, preferably wherein electrically connecting the second contact to the second conductive trace comprises depositing a second conductive material on the electronic component and on the substrate. The electronic component is optionally a light emitting diode (LED) die and the first surface is preferably the active surface of the LED die. The second contact is preferably a backside contact of the LED die, which is preferably on a backside surface of the LED die. Alternatively the backside surface of the LED die is the backside contact. In some embodiments the second contact is optionally on the active surface, and the second conductive trace is then preferably shaped to avoid the first contact and the first conductive material on the active surface. The electrically contacting step preferably comprises disposing the active surface on a thermally and electrically conductive material that electrically connects the second contact to the second conductive trace and that conducts heat produced by the LED die into the substrate. The thermally and electrically conductive material is preferably shaped to avoid the first contact and the first conductive material on the active surface. The method preferably further comprises depositing a light reflecting material on one or more internally reflecting surfaces of the LED die to reflect internal light produced by the active surface of the LED die, thereby increasing light output from the LED die in a predetermined direction. The one or more internally reflecting surfaces comprise optionally one or more sides of the LED die and the predetermined direction is into the substrate.

[0012] Another embodiment of the present invention is an electronic device, the device comprising an electronic component comprising a first contact on a first surface, the first surface disposed against a substrate; a first conductive material contacting the first contact and extending along the first surface to a second surface adjacent to the first surface; and a first electrical connection between the first conductive material on the second surface to a first conductive trace on the substrate. The device preferably further comprises a dielectric or insulating material between the first conductive material and the surfaces of the electronic component. The device preferably comprising a second electrical connection between a second contact of the electronic component and a second conductive trace on the substrate, wherein the second electrical connection preferably comprises a second conductive material deposited on the electronic component and on the substrate. The electronic component is optionally a light emitting diode (LED) die and the first surface is preferably an active surface of the LED die. The second contact is preferably a backside contact of the LED die, which is preferably on a backside surface of the LED die. Alternatively, the backside surface of the LED die forms the backside contact. The second contact is optionally on the active surface, in which case the second conductive trace is preferably shaped to avoid the first contact and the first conductive material on the active surface. The device preferably further comprises a thermally and electrically conductive material between the active surface and the substrate that electrically connects the second contact to the second conductive trace and conducts heat produced by the LED die into the substrate. The thermally and electrically conductive material is preferably shaped to avoid the first contact and the first conductive material on the active surface. The device preferably further comprises a light reflecting material on one or more internally reflecting surfaces of the LED die to reflect internal light produced by the active surface of the LED die, thereby increasing light output from the LED die in a predetermined direction. The one or more internally reflecting surfaces preferably comprise one or more sides of the LED die and the predetermined direction is optionally into the substrate.

[0013] Another embodiment of the present invention is a method of electrically contacting an electronic component, the method comprising providing an electronic component comprising a first surface, the first surface comprising a first contact; creating a first conductive bump in electrical contact with a first conductive strip on a substrate; and mounting the electronic component on the substrate so that the first contact is disposed on the first conductive bump. The first conductive bump preferably comprises conductive adhesive, solder, conductive organic material, or nanoparticle ink. The first conductive strip is preferably an extension or a portion of a first conductive trace on the substrate. The method preferably further comprises depositing a dielectric or insulating material on the first surface adjacent to the first contact or on the first conductive strip to prevent the first conductive strip from electrically contacting the first surface. In some embodiments the first surface comprises a second contact and the method further comprises creating a second conductive bump in electrical contact with a second conductive strip on the substrate, and the mounting step comprises disposing the second contact on the second conductive bump. The second conductive strip is preferably a portion of a second conductive trace on the substrate. The method preferably further comprises depositing a dielectric or insulating material on the first surface adjacent to the second contact or on the second conductive strip to prevent the second conductive strip from electrically contacting the first surface. The method alternatively further comprises electrically connecting a second contact of the electronic component to a second conductive trace on the substrate, the second contact on a second surface of the electronic component, wherein electrically connecting the second contact to the second conductive trace comprises depositing a second conductive material on the electronic component and on the substrate. The electronic component is preferably a light emitting diode (LED) die and the first surface is an active surface of the LED die. The first conductive strip is preferably less than approximately 25 pm wide. The second contact is preferably a backside contact of the LED die which is preferably on a backside surface of the LED die. Alternatively, the backside surface of the LED die comprises the backside contact. The method preferably further comprises depositing a light reflecting material on one or more internally reflecting surfaces of the LED die to reflect internal light produced by the active surface of the LED die, thereby increasing light output from the LED die in a predetermined direction. The one or more internally reflecting surfaces preferably comprise one or more sides of the LED die and the predetermined direction is preferably into the substrate.

[0014] Another embodiment of the present invention is an electronic device, the device comprising an electronic component comprising a first contact on a first surface; and a substrate comprising a first conductive bump in electrical contact with a first conductive strip; wherein the electronic component is mounted on the substrate so that the first contact is disposed on the first conductive bump. The first conductive bump preferably comprises conductive adhesive, solder, conductive organic material, or nanoparticle ink. The first conductive strip is preferably an extension or portion of a first conductive trace on the substrate. The device preferably further comprises a dielectric or insulating material deposited on the first surface adjacent to the first contact or on the first conductive strip to prevent the first conductive strip from electrically contacting the first surface. The first surface optionally comprises a second contact disposed on a second conductive bump that is in electrical contact with a second conductive strip on the substrate, wherein the second conductive strip is preferably a portion or extension of a second conductive trace on the substrate. The device the preferably further comprises a dielectric or insulating material deposited on the first surface adjacent to the second contact or on the second conductive strip to prevent the second conductive strip from electrically contacting the first surface. The device alternatively comprises a second electrical connection between a second contact of the electronic component and a second conductive trace on the substrate, the second contact on a second surface of the electronic component, wherein the second electrical connection preferably comprises a second conductive material deposited on the electronic component and on the substrate. The electronic component is preferably a light emitting diode (LED) die and the first surface is preferably an active surface of the LED die. The first conductive strip is preferably less than approximately 25 pm wide. The second contact is preferably a backside contact of the LED die which is preferably on a backside surface of the LED die. Alternatively, the backside surface of the LED die comprises the backside contact. The device preferably further comprises a light reflecting material on one or more internally reflecting surfaces of the LED die to reflect internal light produced by the active surface of the LED die, thereby increasing light output from the LED die in a predetermined direction. The one or more internally reflecting surfaces preferably comprise one or more sides of the LED die and the predetermined direction is preferably into the substrate.

[0015] Objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate the practice of embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating certain embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

[0017] FIG. 1 is a schematic of a prepackaged LED die, taken from Weissman et al., “Light- Emitting Diodes,” Academic Press, Encyclopedia of Physical Science and Technology (Third Edition), 2003, Pages 539-556. [0018] FIG. 2A is a schematic of the top view of a typical unmounted bare LED die showing the top electrical contact and optically active light emitting areas. FIG. 2B is a schematic of the side view of the die showing the top and bottom electrical contacts and the emission of light in the normally desired upward direction. Osram Opto Semiconductors F3427 datasheet, August 4, 2011.

[0019] FIG. 3 is a schematic of a typical Chip on Board (COB) mounting of an LED bare die on an electrical trace on a substrate board along with a wire bond connecting a second electrical trace on the board to the contact on the active surface of the die.

[0020] FIG. 4 is a schematic of a COB-mounted LED with a printed dielectric and electrical conductor to form a connection from a trace on the board to the contact on the active surface of the die.

[0021] FIG. 5 is a schematic of an LED with printed dielectric and metal conductor that wraps around to a sidewall to enable electrical contact to the active surface contact after the die is inverted and the active surface is placed against a substrate.

[0022] FIG. 6 is a schematic of the LED from FIG. 5 after the active surface is placed against the substrate to aim the light primarily into the substrate.

[0023] FIG. 7 is a schematic of an electrical connection printed to a pre-printed contact line on the side of the die, providing a connection from the conductive trace on the substrate to the obscured contact on the die.

[0024] FIG. 8 is a schematic of an electrical connection to the now-upward-facing second contact of an inverted LED which is located on the now-exposed bottom face of the die (i.e. the side that is normally mounted adjacent to the substrate.)

[0025] FIG. 9 is a schematic of a die making an electrical connection with a trace on a substrate via a small amount of electrically conductive material that bridges between the trace and the contact on the die.

[0026] FIG. 10 is an upward radiating device with an improved thermal connection to the substrate.

[0027] FIG. 11 is a schematic of a die with reflective material coated on one or more of the sidewalls to force the bulk of the light to emerge from the top of the die.

[0028] FIG. 12 is a schematic of a die with reflective material coated on the top surface to force the bulk of the light to emerge from the sidewalls of the die. [0029] FIG. 13 is an inverted die with sidewalls coated with a reflective material to direct light into the substrate.

[0030] FIG. 14 is a schematic of an optionally reflectively coated, transparent chamfer on the side of the die with an optionally reflectively coated top face that directs light emitted from the sidewall downward into the substrate.

[0031] FIG. 15 is a schematic of an LED die with both electrical contacts on the top surface mounted to a transparent substrate. Light is directed out the bottom surface by coating the top and/or side surfaces with a reflective material.

[0032] FIG. 16 is a schematic view of an LED die mounted on its side with connections printed to the exposed top and bottom contacts.

[0033] FIG. 17 is a schematic view of a quad flat no-lead integrated circuit (QFN IC) package with printed electrical contacts wrapped around the sides.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0034] One or more embodiments of the present invention are methods of mounting a preferably bare LED die in an inverted orientation such that the emitted light from the light-creating surface shines primarily downward into the substrate to which the LED is attached, or alternatively orienting the die to shine in another direction. Inverting the die obscures the contact(s) on the creating surface that is then adjacent to, and obscured by, the substrate. One or more embodiments of the present invention preferably enable making an electrical connection to these obscured contacts with a minimum of blockage of the downward traveling light and/or manufacturing reflecting surfaces to direct stray light in the desired direction. As used throughout the specification and claims, the term “light” means any form or wavelength of collimated or uncollimated electromagnetic radiation. As used throughout the specification and claims, the term “electronic component” means semiconductor, semiconductor die, semiconductor component, component die, diode, diode die, light emitting diode (LED), LED die, transistor, integrated circuit, integrated circuit die, flat no-lead package, and the like.

[0035] As used throughout the specification and claims, the term “active surface” means the optically active light-creating surface that is normally mounted upward and facing away from the substrate. As used throughout the specification and claims, the term “backside surface” means the surface opposite the active surface that is normally mounted downward toward or touching the substrate. As used throughout the specification and claims, the terms “backside contact” means the electrical contact on the backside surface, which is typically the current-sourcing contact, cathode, or p-contact, and the term “active contact” means the contact on the active surface, which is typically the current sinking contact, cathode, or n-contact. However, it is understood that devices can be manufactured with the opposite polarity, in which cases the roles of the source and sink features of the LED would be reversed. It is also understood that in some embodiments both electrical contacts can be on the same light-creating face, with no contact on the backside surface.

[0036] FIG. 5 shows the initial stages of manufacture of an embodiment of the present invention on a singulated LED before it is mounted on the final substrate. LED 59 is placed with active surface 54 upward so that active contact 51 and at least one sidewall surface 58 are accessible. If needed to prevent shorting, optional dielectric 57 is printed from active contact 51 across active surface 54 and onto sidewall 58. The dielectric need only cover areas that would cause shorting between the current source and sink when connection 55 is subsequently printed. Connection 55 is then preferably printed from active contact 51 across active surface 54 (or dielectric 57 on active surface 54 if dielectric is necessary), and onto sidewall 58 (or onto dielectric 57 on sidewall 58 if dielectric is necessary). Connection 55 is preferably less than about 25 pm wide to limit the amount of light it blocks; the dielectric is preferably transparent.

[0037] FIG. 6 shows the next stage of manufacture, in which die 59 is preferably rotated from its position in FIG. 5 so that it is now inverted on substrate 74 from its typical orientation (which is shown in, for example, FIGS. 3-4). Die 59 is preferably attached to substrate 64 with a transparent medium (not shown). Active contact 51 is now adjacent to the substrate and cannot be directly accessed, but it is still electrically accessible by previously printed connection 55. FIG. 7 shows printed connection 71 connecting conductive trace 70 on substrate 74 to printed connection 55 on die sidewall 58. In alternative embodiments, both contacts are on the same face of the LED die, typically the active surface. In that embodiment, two connections can be printed on either a common LED die sidewall or differing sidewalls, one connecting each contact to its corresponding conductive trace on the substrate. FIG. 8 shows printed connection 85 from second conductive trace 83 on substrate 74 to backside contact 82 on the exposed surface of the die away from the substrate. Sidewall 88 is shown as being the opposite face from sidewall 58, but any of the sidewalls may be used. Connection 85 need not be insulated via a dielectric layer if the sidewall 88 material is either insulative or shorted to backside contact 82. Likewise, connection 85 need not extend to backside contact 82 if connection 85 makes sufficient electrical connection to sidewall 88. Alternatively, backside contact 82 can be connected to second conductive trace 83 with a wire bond or other connective technique.

[0038] Another embodiment of the present invention is shown in FIG. 9, where the electrical contact between trace 90 and active contact 91 is preferably formed by a three-dimensional bump of conductive material 98 that is printed on conductive trace 95 or on active contact 91. Conductive material 98 may comprise, for example, a conductive adhesive, solder, conductive organic, nanoparticle ink, etc. Conductive trace 95 can either be an extension of conductive trace 90 or a separate printed trace (the latter embodiment shown in the figure). Conductive trace 95 is preferably less than 25 pm wide to limit the amount of light it blocks. If needed to prevent shorting, optional dielectric 97 can be printed before mounting on the active surface of die 99 as shown, or alternatively on trace 95. The process shown in FIG. 8 can then be used to make connect backside contact 92 on the die to its corresponding trace on the substrate. Die 99 is preferably placed at the end of trace 95 to minimize blockage of the downward traveling light by the trace. An insulating or dielectric liquid underfill (not shown) is preferably applied to mechanically stabilize the structure and electrically insulate the active face. If this underfill wicks partially up the side of the die it can provide the electrical insulation which may be required to print a connection to backside contact 92. In another alternative embodiment, the conductive material process described herein can be duplicated if both contacts are present on the active surface and thus are both adjacent to the substrate.

[0039] While FIGS. 5-9 represent embodiments that minimize the blockage of light being emitted downward into the substrate, the method of connecting to an obscured contact is also useful when mounting upward radiating power devices whose active surface is adjacent to a trace that acts as a heat sink. FIG. 10 shows LED die 109 with active surface 104 oriented towards trace 100, which also radiates upward since light is emitted from both sides of the active surface. N-contact 102 and active surface 104 are connected electrically and preferably thermally to trace 100 by electrically and thermally conductive material 108, which can be deposited either on trace 100 or on LED die 109. Conductive material 108 and/or trace 100 can be shaped to avoid electrical shorting with p-contact 101, or alternatively an insulating dielectric (not shown) can be printed as needed. P-contact 101 is electrically connected to trace 103 preferably in the same manner as is shown in FIG. 7.

[0040] An embodiment of the present invention involving reflective surfaces is shown in FIG.

11. Active surface 114 and active contact 111 are facing up away from the substrate 110 and backside contact 112 contacts substrate 110. Sidewall 118 and preferably the other sidewalls are coated with material 115 that reflects the light internally that would normally leave the sidewall surface. Light that would normally exit the sidewalls is thus either absorbed internally within LED die 119 or exits as emitted light 116 out of active surface 114. This is particularly beneficial when use of an external reflecting surface such as reflecting cup 12 in FIG. 1A is not desirable for some reason. In an alternative embodiment (not shown), the backside surface of the LED can be reflectively coated as well if the backside contact is not on the bottom surface as shown, but is instead a second contact on the active surface. These reflective surfaces preferably direct most of the emitted light out the top surface of the LED. In FIGS. 11-16 the light reflecting material is shown to be partially coating a surface, such as a sidewall. However, the entirety of a surface (preferably except for any contacts or conductive strips) may optionally be coated.

[0041] An alternative embodiment of this invention can be used to force most of the emitted light out of the sidewalls of the die. FIG. 12 shows an LED with reflective coating 125 on active surface 124 with light 112 being emitted from one or more sidewalls 128. Similarly, most of the emitted light can be forced to be emitted into the substrate beneath the die. FIG. 13 shows inverted die 139 comprising sidewalls 138 coated with reflective material 135 so that most of the light 136 is forced into substrate 134. Electrical connections can be made as described in the previous embodiments.

[0042] FIG. 14 shows LED die 149 with transparent structure 141 for directing light 146 emitted from the sidewall 148 down into substrate 142. Structure 141 preferably comprises a 45- degree chamfer and is preferably coated with light reflecting material 145. Active surface 144 can optionally be coated with non-conductive reflecting material 143. Although not shown, the sidewalls of LID die 149 are also preferably coated with light reflecting material.

[0043] FIG. 15 shows die 159 mounted with active surface 154 mounted away from substrate 150. Some or all of active surface 154 and sidewalls 158 are coated with reflective material 153 that directs light 155 thru backside surface 157 and into substrate 150. Backside surface 157 can be transparent because n-contact 151 and p-contact 152 are both on active surface 154.

[0044] FIG. 16 shows a die 169 mounted on one of the sidewalls with reflecting material 163 coating some or all of the exposed surfaces. Light from active surface 164 is reflected from the exposed surfaces and light 166 exits down into substrate 160.

[0045] The methods shown in these embodiments, including the use of reflecting surfaces, can also be of benefit to larger devices and non-LED devices, such as power devices or integrated circuit dies, whose electrical contacts are located in positions that are inconvenient to access when the device is mounted in a desirable configuration. For example, FIG. 17 shows quad flat no-lead integrated circuit (QFN IC) package 170 with electrical contacts 171. These devices are normally soldered with contacts 171 facing the substrate by surface mount techniques. A portion of each contact 171 may not be exposed, or only a portion too small to easily connect to may be exposed, on sidewall 173 of the package. Wrapping printed connection 172 onto sidewall 173 of the package allows connections to be made in the manner shown in FIG. 7 when the contacts on the top face of QFN IC package 170 are disposed against the substrate. This technique can be used on semiconductor circuits that have electrical contacts that are obscured, included integrated circuits.

[0046] The precision, fully 3-D deposition of the reflecting material is preferably performed using Aerosol Jet® technology, although any materials deposition technology may be employed. The reflective material can be either conductive (e.g. silver) or non-conductive. A conductive material must be deposited in such a way as to avoid shorting the device. Alternately, dielectric material can be printed or deposited before deposition of a conductive reflecting material to prevent shorting. In some cases, the dielectric can be applied as a blanket in a batch process with some means of exposing covered contacts as needed, e.g. a parylene coating with laser opened contacts. A non-conducting reflecting material can be printed or deposited without the concern of creating shorts. [0047] Note that in the specification and claims, “about” or “approximately” means within twenty percent (20%) of the numerical amount cited. As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a functional group” refers to one or more functional groups, and reference to “the method” includes reference to equivalent steps and methods that would be understood and appreciated by those skilled in the art, and so forth.

[0048] Although the invention has been described in detail with particular reference to the disclosed embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover all such modifications and equivalents. The entire disclosures of all patents and publications cited above are hereby incorporated by reference.

Claims

1 . A method of electrically contacting an electronic component, the method comprising: depositing a first conductive material on the electronic component, the first conductive material contacting a first contact on a first surface of the electronic component and extending to a second surface adjacent to the first surface; mounting the first surface against a substrate; and electrically connecting the first conductive material on the second surface to a first conductive trace on the substrate.

2. The method of claim 1 further comprising depositing a dielectric or insulating material prior to depositing the conductive material and subsequently depositing the conductive material on the dielectric or insulating material, the dielectric or insulating material extending from the first contact to the second surface.

3. The method of claim 1 further comprising electrically connecting a second contact of the electronic component to a second conductive trace on the substrate.

4. The method of claim 3 wherein electrically connecting the second contact to the second conductive trace comprises depositing a second conductive material on the electronic component and on the substrate.

5. The method of claim 3 wherein the electronic component is a light emitting diode (LED) die and the first surface is an active surface of the LED die.

6. The method of claim 5 wherein the second contact is a backside contact of the LED die.

7. The method of claim 6 wherein the backside contact is on a backside surface of the LED die.

8. The method of claim 6 wherein the backside surface of the LED die comprises the backside contact.

9. The method of claim 5 wherein the second contact is on the active surface.

10. The method of claim 9 wherein the second conductive trace is shaped to avoid the first contact and the first conductive material on the active surface.

11 . The method of claim 9 wherein the electrically contacting step comprises disposing the active surface on a thermally and electrically conductive material that electrically connects the second contact to the second conductive trace and that conducts heat produced by the LED die into the substrate.

12. The method of claim 11 wherein the thermally and electrically conductive material is shaped to avoid the first contact and the first conductive material on the active surface.

13. The method of claim 5 further comprising depositing a light reflecting material on one or more internally reflecting surfaces of the LED die to reflect internal light produced by the active surface of the LED die, thereby increasing light output from the LED die in a predetermined direction.

14. The method of claim 13 wherein the one or more internally reflecting surfaces comprise one or more sides of the LED die and the predetermined direction is into the substrate.

15. An electronic device, the device comprising: an electronic component comprising a first contact on a first surface, the first surface disposed against a substrate; a first conductive material contacting the first contact and extending along the first surface to a second surface adjacent to the first surface; and a first electrical connection between the first conductive material on the second surface to a first conductive trace on the substrate.

16. The device of claim 15 further comprising a dielectric or insulating material between the first conductive material and the surfaces of the electronic component.

17. The device of claim 15 comprising a second electrical connection between a second contact of the electronic component and a second conductive trace on the substrate.

18. The device of claim 17 wherein the second electrical connection comprises a second conductive material deposited on the electronic component and on the substrate.

19. The device of claim 17 wherein the electronic component is a light emitting diode (LED) die and the first surface is an active surface of the LED die.

20. The device of claim 19 wherein the second contact is a backside contact of the LED die.

21 . The device of claim 20 wherein the backside contact is on a backside surface of the

LED die.

22. The device of claim 20 wherein the backside surface of the LED die comprises the backside contact.

23. The device of claim 19 wherein the second contact is on the active surface.

24. The device of claim 23 wherein the second conductive trace is shaped to avoid the first contact and the first conductive material on the active surface.

25. The device of claim 23 further comprising a thermally and electrically conductive material between the active surface and the substrate that electrically connects the second contact to the second conductive trace and conducts heat produced by the LED die into the substrate.

26. The device of claim 25 wherein the thermally and electrically conductive material is shaped to avoid the first contact and the first conductive material on the active surface.

27. The device of claim 19 further comprising a light reflecting material on one or more internally reflecting surfaces of the LED die to reflect internal light produced by the active surface of the LED die, thereby increasing light output from the LED die in a predetermined direction.

28. The device of claim 27 wherein the one or more internally reflecting surfaces comprise one or more sides of the LED die and the predetermined direction is into the substrate.

29. A method of electrically contacting an electronic component, the method comprising: providing an electronic component comprising a first surface, the first surface comprising a first contact; creating a first conductive bump in electrical contact with a first conductive strip on a substrate; and mounting the electronic component on the substrate so that the first contact is disposed on the first conductive bump.

30. The method of claim 29 wherein the first conductive bump comprises conductive adhesive, solder, conductive organic material, or nanoparticle ink.

31 . The method of claim 29 wherein the first conductive strip is a portion of a first conductive trace on the substrate.

32. The method of claim 29 further comprising depositing a dielectric or insulating material on the first surface adjacent to the first contact or on the first conductive strip to prevent the first conductive strip from electrically contacting the first surface.

33. The method of claim 29 wherein, when the first surface comprises a second contact, the method further comprises creating a second conductive bump in electrical contact with a second conductive strip on the substrate, and the mounting step comprises disposing the second contact on the second conductive bump.

34. The method of claim 33 wherein the second conductive strip is a portion of a second conductive trace on the substrate.

35. The method of claim 33 further comprising depositing a dielectric or insulating material on the first surface adjacent to the second contact or on the second conductive strip to prevent the second conductive strip from electrically contacting the first surface.

36. The method of claim 29 further comprising electrically connecting a second contact of the electronic component to a second conductive trace on the substrate, the second contact on a second surface of the electronic component.

37. The method of claim 36 wherein electrically connecting the second contact to the second conductive trace comprises depositing a second conductive material on the electronic component and on the substrate.

38. The method of claim 36 wherein the electronic component is a light emitting diode (LED) die and the first surface is an active surface of the LED die.

39. The method of claim 38 wherein the first conductive strip is less than approximately 25 pm wide.

40. The method of claim 38 wherein the second contact is a backside contact of the LED die.

41 . The method of claim 40 wherein the backside contact is on a backside surface of the LED die.

42. The method of claim 40 wherein the backside surface of the LED die comprises the backside contact.

43. The method of claim 38 further comprising depositing a light reflecting material on one or more internally reflecting surfaces of the LED die to reflect internal light produced by the active surface of the LED die, thereby increasing light output from the LED die in a predetermined direction.

44. The method of claim 43 wherein the one or more internally reflecting surfaces comprise one or more sides of the LED die and the predetermined direction is into the substrate.

45. An electronic device, the device comprising: an electronic component comprising a first contact on a first surface; and a substrate comprising a first conductive bump in electrical contact with a first conductive strip; wherein the electronic component is mounted on the substrate so that the first contact is disposed on the first conductive bump.

46. The device of claim 45 wherein the first conductive bump comprises conductive adhesive, solder, conductive organic material, or nanoparticle ink.

47. The device of claim 45 wherein the first conductive strip is a portion of a first conductive trace on the substrate.

48. The device of claim 45 further comprising a dielectric or insulating material deposited on the first surface adjacent to the first contact or on the first conductive strip to prevent the first conductive strip from electrically contacting the first surface.

49. The device of claim 45 wherein the first surface comprises a second contact disposed on a second conductive bump that is in electrical contact with a second conductive strip on the substrate.

50. The device of claim 49 wherein the second conductive strip is a portion of a second conductive trace on the substrate.

51 . The device of claim 49 further comprising a dielectric or insulating material deposited on the first surface adjacent to the second contact or on the second conductive strip to prevent the second conductive strip from electrically contacting the first surface.

52. The device of claim 45 comprising a second electrical connection between a second contact of the electronic component and a second conductive trace on the substrate, the second contact on a second surface of the electronic component.

53. The device of claim 52 wherein the second electrical connection comprises a second conductive material deposited on the electronic component and on the substrate.

54. The device of claim 52 wherein the electronic component is a light emitting diode (LED) die and the first surface is an active surface of the LED die.

55. The device of claim 54 wherein the first conductive strip is less than approximately 25 pm wide.

56. The device of claim 54 wherein the second contact is a backside contact of the LED die.

57. The device of claim 56 wherein the backside contact is on a backside surface of the LED die.

58. The device of claim 56 wherein the backside surface of the LED die comprises the backside contact.

59. The device of claim 54 further comprising a light reflecting material on one or more internally reflecting surfaces of the LED die to reflect internal light produced by the active surface of the LED die, thereby increasing light output from the LED die in a predetermined direction.

60. The device of claim 59 wherein the one or more internally reflecting surfaces comprise one or more sides of the LED die and the predetermined direction is into the substrate.