DE102019133203B4 - UV LED array with power connector connection and heat sink - Google Patents

Abstract

A heat sink and power connector for a UV LED array, comprising:a first substrate selected from an electrically insulating material or an electrically conductive material having one or more electrically insulating layers thereon;a first circuit comprising located on a surface of the first substrate;a UV LED array located on a portion of the first circuit or on the surface of the first substrate, the UV LED array being in electrical communication with the first circuit;a second substrate, spaced from the first substrate;a second circuit located on a surface of the second substrate;at least a first heat sink configured to conduct heat away from the UV LED array, the heat sink being adjacent to the first substrate and/or the second substrate is located;an opening through the first substrate, the second substrate and extending through the at least one first heat sink;an electrical insulator lining the opening;an electrically and thermally conductive liner located adjacent to the electrical insulator;a fastener located in the opening and connected to the electrically and thermally conductive liner in is in contact, wherein the fastener electrically connects the first circuit and the second circuit to one another via the electrically and thermally conductive liner and electrically communicates with an external power source, the fastener carrying power from the power source and/or an electrical signal and heat via the electrically and thermally conductive liner to the at least one first heat sink.

Description

Field of Invention:

The present invention relates to electrical connections in device assemblies and more particularly to electrical connections in high power device assemblies such as UV LED arrays.

Background:

Many electronic devices and electrical devices use a variety of wire-based connectors to communicate with power sources or with other electrical devices. However, as these devices get smaller in footprint, there is higher power density and cable connections can be difficult to make and maintain. Furthermore, high power densities can generate large amounts of heat that can damage solder joints holding wires. For example, traditional LEDs use different wire connections between a power source and the LED module. However, this cable connection is a source of failure, particularly with solder joints, terminals with wires, or connectors with cable connections that can be weakened due to thermal fatigue or mechanical stress. Cable connections are also a source of defective products during manufacture. Unlike traditional lighting approaches, LED lighting techniques have relatively high efficiency, which generates less heat. However, the newly developed UV LEDs, which produce some very short wavelengths below 400 nm, typically have relatively low conversion efficiencies, thereby generating large amounts of heat. In order to improve efficiency and keep a compact structure, a new design for integrating the power path with heat dissipation functions is important. As used herein, the term "UV" refers broadly to all forms of UV radiation including UV, UV-A, UV-B, UV-C, near UV, etc. In general, the term "UV" applies to wavelengths of approximately 10 nm to about 440 nm.

U.S. 2013/0051020 A1 deals with an LED lighting fixture and shows in the figures arrays of LEDs on a printed circuit board as a first substrate with first circuits and connected to a housing as a heat sink by means of screws as fastening means through openings.

TW 2012/48947A reveals LED modules for high power and shows in 1 , that the LEDs are arranged on a printed circuit board, which are connected to a heat sink via screws.

WO 2014/031095 A1 describes micro-channel-cooled UV LED arrays for UV curing systems with output powers of 10 to 100 W/cm ² and waste heat of 100 to 10,000 W/cm ² and also shows a structure with an LED array in the figures , consisting of the LEDs on a heat sink layer over the microchannel cooler and with anode and cathode leads attached to each other by screws.

WO 2017/211773 A1 discloses UV LED arrays for water sanitation. the 1 until 5 show a structure with UV LEDs attached to lines on the cover window as the first substrate and connected to a printed circuit board via spring contacts. the 7 sets the spring contact in a through hole through the circuit board for external contact. In the 7 Assembly 96 shows this via going through the housing.

In conventional techniques for UV applications, one would normally use organic materials (e.g. insulation jackets for electrical cables, insulation materials of plugs, sockets or terminal blocks) as connection materials. However, UV light and heat cause degradation under long-term exposure to short-wavelength illumination, and new designs are needed that improve heat dissipation while facilitating compact design.

Current UV arrays may use ceramic substrates to reduce thermal effects, but there are drilled holes for connection when connectors are used. Too much heat can create the dangers of cracking at connector locations.

Furthermore, when LEDs are used in large arrays, significant heat is generated because the high power density is concentrated in a small area. This heat, particularly the extreme thermal cycling as the devices are heated and cooled, can damage conventional interconnects. Also, unstable connections can fail, such as those due to poor soldering or misalignment of wires and solder.

LED arrays also produce significant amounts of light. In some cases, the amount of light produced can be two orders of magnitude greater than full sunlight in the middle of the day. This amount of light can also damage soldered wire connections, causing power failures in LED arrays.

Therefore, there is a need in the art for improved electrical connections between LEDs and power sources.

Furthermore, there is a need for improved connection structures for other systems that are currently connected by cables. That said, improved interconnect structure has numerous applications beyond LEDs and LED arrays.

There is a further need to improve efficiency and maintain compact device structures, and in particular a need for a new design to integrate a current path with heat dissipation functions.

Brief description of the invention

The present invention provides a heat sink and power connector connection for a UV LED array. A first substrate is selected from a circuit board, ceramic or glass ceramic material. A first circuit is on a surface of the first substrate. A UV LED array is located on a portion of the first circuit or on the surface of the first substrate, with the UV LED in electrical communication with the first circuit.

A second substrate is spaced from the first substrate, with second circuitry on a surface of the second substrate. At least one first heat sink configured to dissipate heat from the UV LED array is adjacent to the first substrate and/or the second substrate. An opening extends through each of the first substrate, the second substrate, and the heat sink. An electrical insulator lines the opening with an electrically and thermally conductive lining located adjacent to the electrical insulator.

An electrically and thermally conductive fastener is located in the opening and contacts the electrically and thermally conductive liner such that the fastener electrically connects the first circuit and the second circuit through the electrically and thermally conductive liner and electrically to an external power source communicates, carries power and/or an electrical signal, and dissipates heat via the electrically and thermally conductive liner to the at least one first heat sink.

character list

• 1 shows schematically a fastener connection according to an embodiment of the present invention;
• 2 shows schematically a fastener connection according to another embodiment of the present invention;
• the 3A-3F show schematically a UV LED array with a fastener connection according to an embodiment of the present invention;
• 4 FIG. 12 shows schematically a UV LED array with a fastener connection according to another embodiment of the present invention; FIG.
• 5 Fig. 12 shows schematically a thermocouple probe with a fastener connection according to an embodiment of the present invention;
• 6 shows schematically details of an actively cooled heat sink with fastener connections according to an embodiment of the present invention;
• 7A Fig. 12 schematically shows a cross-sectional view of a thin film heater with a fastener connection according to an embodiment of the present invention;
• 7B 12 schematically shows a perspective view of a thin film heater according to an embodiment of the present invention.

Detailed description

We now turn to the drawings in detail; 1 Figure 1 shows an overview of a conductive fastener assembly that overcomes the disadvantages of conventional wiring. The conductive fastener is mechanically robust and easily mounts to circuit boards and other substrate materials. As will be discussed in more detail below, the fastener can provide a connection between circuitry that connects to an LED (or other device that needs to communicate with a power source) and other circuitry located on another surface of the circuit board or substrate are or may be on another substrate.

In the example of 1 A first substrate 10 may be selected from printed circuit boards such as FR-X (PCB) or CEM-X (PCB), or it may be a ceramic such as aluminum nitride, silicon carbide or aluminum oxide/sapphire. Others don't electrically conductive substrates can also be selected, such as certain polymers, glass-ceramics, or metals with insulating ceramic or polymer layers thereon. A conductive material 20 is located on the substrate 10 and may be patterned into a first electrical circuit. A second substrate 30 is located away from the first substrate 10 . Like substrate 10, substrate 30 may be selected from circuit boards, ceramics, or other non-conductive materials. Another conductive layer 40 is located on the second substrate 30 and can be structured into a second electrical circuit. The conductive layers can be copper, gold, silver, or alloys thereof, or any other material with sufficient conductivity to carry electrical signals or power to a device residing on the substrates or the conductive layers.

In 1 For example, substrates 10 and 30 are on either side of a core/heat sink of thermally conductive material 50. Typically, the core is selected from a metal core such as aluminum alloy, aluminium, copper, copper alloy or stainless steel, but other conductive materials including non-metals may also be used be used. Although the substrates are on either side of the core/heat sink of conductive material, other configurations are acceptable, including those where one or both substrates are not in direct contact with the heat sink or are in contact with the heat sink via one or more intermediate layers are contact.

An opening 60 extends through the first and second substrates 10, 30 and the first and second conductive layers 20, 40 and the heat sink 50. An electrical insulator 65 lines the opening with an electrically and thermally conductive liner 70 which is adjacent on the electrical insulator. The electrical insulator 65 can be a ceramic or polymer insulator, although other insulating materials can also be used. The electrically and thermally conductive liner may be a metal such as copper, copper alloys, aluminum, aluminum alloys, nickel, steel, or conductive non-metals.

An electrically and thermally conductive fastener 80 is located in the opening 60 where it contacts the electrically and thermally conductive liner 70 so that the fastener 80 connects the first circuit (conductor 20) and the second circuit (conductor 40) via the electrically and thermally conductive panel 70 electrically connected to each other. For example, the fastener 80 may be a threaded fastener, such as a screw or bolt, or it may be an unthreaded fastener.

how to get in 2 recognizes, additional circuitry and heat sinks can also be interconnected to obtain more complex multilayer structures. In 2 For example, the electrically and thermally conductive liner 70 extends through a second opening 160 that extends through a second heat sink 150 and third and fourth substrates 110 and 130, respectively. These third and fourth substrates comprise third and fourth conductive layers (optionally patterned into circuits), elements 120 and 140 in FIG 2 . Although it's in 2 Although not shown, it should be understood that other substrates and circuits may be interconnected via the electrically and thermally conductive cladding and fasteners 80,180, with or without additional heat sinks.

In the embodiment of 2 the circuit boards are separated from each other by heat sinks and also air. There may be another heat sink between plates 30 and 110, however. Other objects (e.g. additional substrate material) can be used to physically maintain or fix all structures in a stable state. Note that each substrate can include more than one circuit. The amount of fasteners is selected based on the circuitry that will be interconnected on the substrates. For existing high-performance consumer electronic devices, there are numerous cables that contain signals or power, and these cables add complexity to the system, make the system difficult to maintain or repair, and are sources of potential system failure. The conductive fastener connection system improves reliability. Fastener 80 may be a unitary/integral structure having a head and shank, or the head and shank may be separable as shown at head 84 and shank 82 . The head 84 can be a nut that can engage one or more shafts, as in the connection of the two structures in FIG 2 is shown. Note that although not shown, the use of the stem alone without a header may be desirable in some circuit configurations. That is, the use of the term "fastener" is broadly the use of any element that can connect parts together and does not denote a particular structure. The fastener acts as a mechanical, electrical, and thermal connector. When using a two-piece fastener, the installation of the fastener can be different from that of a one-piece fastener ments can be different, that is, the shank portion 82 can be inserted into an opening and then the head can be attached. A single head can be connected to multiple shafts which can be assembled separately and then connected together via the head.

The fasteners and the electrically and thermally conductive shroud 70 electrically communicate with an external power source 200. The shroud 70 carries power and/or an electrical signal and conducts heat through the electrically and thermally conductive shroud to the first heat sink 50 (and into 2 to the second heat sink 150).

the 3A-3F show the system of 1 , which is used in a UV LED array 300 according to an aspect of the present invention. The UV LED array 300 includes a plurality of UV LEDs 310 arranged in rows (although other arrangements may be used) on a substrate 330 . A circuit 320 is on a substrate 330. Depending on the type of UV LEDs, the LEDs 310 are on the substrate 330 or on the circuit 320 or partly on the circuit and partly on the substrate 330. In 3A Optionally, there is a glass cover 340 over the UV LEDs 310. Above the glass cover is an optional lens or array of lenses or diffusers 350.

How to get into the 3A , 3D and 3F 1, apertures 370 pass through substrates 330. As can be seen in these figures, conductive circuit 320 is in contact with conductive fastener 380, which then conducts power or signals through conductive shroud 365. FIG.

4 FIG. 4 shows an aspect of a UV LED array 400 using “flip chip” bonding to further eliminate wire bonded connections. The UV LEDs 410 include bonding pads 415 connected to circuitry 420 located on the substrate 430 .

The UV LED array with the conductive mounting system can be used in a variety of UV lithography devices such as those described in US Pat U.S. 9,128,387 B2 and US patent application U.S. 2010/0 283 978 A1 , the disclosures of which are incorporated herein by reference. Alternatively, the UV LED arrays from 3 and 4 used in UV curing systems and UV medical devices. In principle, the UV LED array incorporating the conductive attachment interconnect system of the present invention can be used in any device that requires a UV source, and is particularly useful for devices that require a high intensity UV source.

The flexibility of the present invention provides excellent reliability performance that is particularly well suited to high power density applications (e.g., greater than 30 watts/cm ² in some embodiments and greater than 60 watts/cm ² in other embodiments). It is also suitable for tabletop dependent UV LED array applications such as UV curing, offset printing, UV sources for lithography or thin film heat generators. The configuration of the connection allows for the use of advanced thermal management techniques including cooling tubes for gas or water, which may or may not be embedded in the thermal conductivity layer. Furthermore, the conductive fastener connection system can also be used with irregularly shaped substrates and circuit patterns.

The LED connection system is used in a variety of LED applications, such as lighting. In particular, the system is useful for LED array based lighting, such as tubes used to replace conventional fluorescent tubes and other lighting intended to replace incandescent bulbs. In general, all lighting applications that currently use cables to deliver power to the LED can take the place of the conductive fastener and conductive tube structures to power individual LEDs or LED arrays.

In summary, the interconnection system of the present invention can be used with (i) high current, high power (e.g., 1 amp to about 20-30 A) consumer applications and with (ii) a small operating range resulting in high energy density and power density ( can be used up to the thermal limit of the selected substrate or substructure of a power-consuming device); (iii) the conductive fasteners are used as the connection interface, with performance and reliability superior to traditional soldering or plug-in or clamp-on methods.

5 Figure 1 shows another application of the connection system of the present invention. 5 Figure 12 shows a high thermal energy producing device 500, such as an array of UV LEDs 510 (although any other high thermal energy producing device may be used). The device 500 includes a conductive circuit layer 520 and a substrate layer 530. A optional heat sink layer 550 may also be included. In one aspect, a thermocouple 590 associated with a fastener 580, an insulator 570, and a thermally and electrically conductive liner 560 measures temperatures beneath the substrate 530, while other thermocouples may measure temperatures at the surface of the substrate 530.

6 Figure 12 shows an embodiment of the present invention using an actively cooled heat sink. 6 Figure 12 shows a high thermal energy producing device 600, such as an array of UV LEDs 610 (although any other high thermal energy producing device may be used). A substrate 630 is located adjacent to the actively cooled heat sink 650. The fastener connection system of fastener 680, insulating sleeve 670, and an electrically and thermally conductive liner 660 is located in an opening that extends through the substrate 630 and the heat sink 650. Actively cooling conduits 655 reside within heat sink 650 and can carry cooling fluid, such as cooling gas or cooling liquid, through heat sink 650 . In this way, a larger amount of heat can be dissipated than with passively cooled heat sinks. Note that the actively cooled heat sink of 6 with any of the other embodiments of the present invention employing a heat sink.

the 7A and 7B show a thin film heater element 700 employing the interconnection system of the present invention. As can be seen in these figures, a conductive thin film as a resistance heater 740 is on the substrate 730; the substrate may be an insulating substrate such as glass or ceramic or glass-ceramic material. The resistive heating layer may be a nickel-chromium alloy (eg, an alloy of approximately 80 percent nickel and 20 percent chromium) or any other resistive heating material (eg, aluminum, aluminum alloys, indium tin oxide, tantalum nitride). Fastener 780 enters through substrate 730 into an opening in element 750; element 750 may be thermally conductive and act as a heat sink. The opening includes a sleeve of insulator 770 and an electrically and thermally conductive liner 760.

In summary, the present invention has particular application with UV modules/power modules for UV sources or arrays that have high current ratings, for example from about 1A to 2A current, up to about 100A current. A specific current carrying capacity depends on various criteria such as voltage, working area, fastener dimension, types of substrate materials and the voltage/current relationship. Furthermore, small work surfaces can use the fasteners of the present invention with a reduction in space over conventional wire bonds. For example, an LED module with dimensions of approximately 4×5 cm, 20 cm ² , approximately 60-100 W with an electrical power density of 3-5 W/cm ² (for an M3 screw size) in the fastening systems of FIG 1 and 2 easily accommodated. One should be aware that larger fasteners, such as M5 and M10 bolt sizes, can handle proportionately larger power densities.

Other applications for the conductive fastener connection system include facilitating connection between batteries used, for example, in electric motor applications. Other applications include use as interconnects in modules in data centers (e.g. connecting server racks in data centers). The connection system can also be used with other high power loads such as lasers or certain high power semiconductor devices. The broad applications for the present invention can eliminate the need for many wires, terminals, or connectors in present electronic assemblies.

Advantages of the present invention are high reliability, particularly long term reliability, under the severe conditions of high UV exposure and repeated thermal cycling. It is also resistant to vibration and aging conditions. Because it has eliminated the need for various solder joints, there is no wire classification and maintenance is easy as fasteners can be easily removed and replaced. Work surface is also improved as fasteners can be recessed from the fixture surface. Numerous other applications may incorporate the fastener linkage system including power electronics, connections between batteries, wire replacement in rack systems, fan assemblies, etc.

Furthermore, a smaller amount of interface on the circuit substrates can be achieved. Advantageously, heat dissipation would be limited at interface materials such as glue, device pads compared to prior art designs having connectors or clamp terminals or any wires. The use of the invention Fastener connection can reduce the risks of cracking because the surface area of the fastener is greater than prior art connectors or other prior art connection methods. Thus, the locking joint of the present invention that reduces the interface area is important to improve heat dissipation problems and improve reliability while extending the life of the devices using the fasteners.

Claims (18)

A heat sink and power connector connection for a UV LED array, comprising: a first substrate selected from an electrically insulating material or an electrically conductive material having one or more electrically insulating layers thereon; a first circuit located on a surface of the first substrate; a UV LED array located on a portion of the first circuit or on the surface of the first substrate, the UV LED array in electrical communication with the first circuit; a second substrate spaced from the first substrate; a second circuit located on a surface of the second substrate; at least one first heat sink configured to dissipate heat from the UV LED array, the heat sink being adjacent to at least one of the first substrate and the second substrate; an opening extending through each of the first substrate, the second substrate, and the at least one first heat sink; an electrical insulator lining the opening; an electrically and thermally conductive liner located adjacent to the electrical insulator; a fastener located in the opening and in contact with the electrically and thermally conductive liner, the fastener electrically connecting the first circuit and the second circuit through the electrically and thermally conductive liner and electrically communicating with an external power source, wherein the fastener carries power from the power source and/or an electrical signal and conducts heat through the electrically and thermally conductive liner to the at least one first heat sink. Heat sink and power connector connection for a UV LED array according to FIG claim 1 , wherein the heat sink is adjacent to the first substrate and the second substrate such that the first substrate is on a first surface of the heat sink and the second substrate is on a second surface of the heat sink. Heat sink and power connector connection for a UV LED array according to FIG claim 1 , wherein the second substrate is spaced from the heat sink. Heat sink and power connector connection for a UV LED array according to FIG claim 3 , further comprising a second fastener cooperating with the second substrate. Heat sink and power connector connection for a UV LED array according to FIG claim 4 , further comprising a second heat sink located adjacent to the second substrate. Heat sink and power connector connection for a UV LED array according to FIG claim 1 wherein the heat sink comprises one or more metals selected from copper, aluminum, steel, stainless steel or alloys thereof. Heat sink and power connector connection for a UV LED array according to FIG claim 1 wherein the first and second substrates are each independently selected from ceramics, glass-ceramics, polymers or metals coated with electrically insulating layers. Heat sink and power connector connection for a UV LED array according to FIG claim 1 wherein the first and second substrates are each independently selected from circuit board, alumina, silicon carbide, aluminum nitride, cordierite or glass. Heat sink and power connector connection for a UV LED array according to FIG claim 1 , where either the electrical insulator or the electrically and thermally conductive liner is a tube located in the opening. A combined terminal connection and heat sink for high power devices, comprising: a first substrate selected from an electrically insulating material or an electrically conductive material having one or more electrically insulating layers thereon; a first circuit located on a surface of the first substrate; a device generating a lot of heat consisting of a device using a current of 1 ampere or more, or a device device that generates heat in excess of about 30 watts/cm ² , wherein the high heat generating device is selected from one or more of a UV LED, a visible LED, a laser, or a thin film heater located on a portion of the first circuit or on the surface of the first substrate and electrically communicating with the first circuit is selected; a second substrate selected from an electrically insulating material or an electrically conductive material having one or more electrically insulating layers thereon and spaced from the first substrate; a second circuit located on a surface of the second substrate; a heat sink configured to dissipate heat from the high heat generating device, the heat sink being adjacent to at least one of the first substrate and the second substrate; an opening passing through each of the first substrate, the second substrate and the heat sink; an electrical insulator lining the opening; an electrically and thermally conductive liner located adjacent to the electrical insulator; a fastener located in the opening and in contact with the electrically and thermally conductive liner, the fastener electrically connecting the first circuit and the second circuit through the electrically and thermally conductive liner and electrically communicating with an external power source, wherein it carries power and/or an electrical signal and dissipates heat to the heat sink via the electrically and thermally conductive liner. Combined terminal connection and heat sink for high power devices according to claim 10 , wherein the heat sink is adjacent to the first substrate and the second substrate such that the first substrate is on a first surface of the heat sink and the second substrate is on a second surface of the heat sink. Combined terminal connection and heat sink for high power devices according to claim 10 , wherein the second substrate is spaced from the heat sink. Combined terminal connection and heat sink for high power devices according to claim 10 , further comprising a second fastener cooperating with the second substrate. Combined terminal connection and heat sink for high power devices according to claim 12 , further comprising a second heat sink located adjacent to the second substrate. Combined terminal connection and heat sink for high power devices according to claim 10 wherein the first and second substrates are each independently selected from ceramics, glass-ceramics, polymers or metals coated with electrically insulating layers. Combined terminal connection and heat sink for high power devices according to claim 10 wherein the heat sink comprises one or more metals selected from copper, aluminum, steel, stainless steel or alloys thereof. Combined terminal connection and heat sink for high power devices according to claim 10 wherein the first and second substrates are each independently selected from circuit board, alumina, silicon carbide, aluminum nitride, cordierite or glass. Combined terminal connection and heat sink for high power devices according to claim 10 , where either the electrical insulator or the electrically and thermally conductive liner is a tube located in the opening.

Images