Patent Application
20090073713
1. Field of the Invention
The present invention generally relates to substrate assemblies. More specifically, the invention relates to substrate assemblies having a plurality of light-emitting diodes (LEDs) integrated therewith.
2. Description of Related Art
Light-emitting diodes (LEDs) are fast becoming a preferable light source for automotive lighting applications, as they consume less power than other forms of light sources, but still provide light output that is acceptable for automotive applications. Currently, multiple LEDs are used as light sources to perform many of the signal lighting applications in motor vehicles. Use of several LEDs in a single application may provide desired styling themes and lit appearances. Lamps used for exterior lighting on motor vehicles often have curved lenses. Using multiple LEDs with curved lenses, however, increases complexity of packaging, which increases the overall cost of the lighting systems. Typically, in order to provide adequate light intensity, an LED must be positioned near the interior surface of the lens.
Conventional ways of positioning LEDs near the interior surfaces of curved lenses include: 1) using multiple planar circuit boards positioned on a heat sink step pattern with wire jumper interconnects; 2) using metal core boards that are formed into a three-dimensional pattern; 3) using a flex circuit to drape LEDs onto a three-dimensional heat sink; and 4) using a lead frame to form LEDs into a three-dimensional pattern on planar patches. All of these methods are equipment intensive, and these types of substrates cost more than standard flat substrates. Assembly of three-dimensional substrates is complicated, which is not compatible with mass production. Unique robots may be required to place parts, and the defect rate for these is relatively high.
One solution to the complexities involved with three-dimensional substrates is a rigid flex printed wiring board. This type of board is relatively stiff, but it may be flexed into a slightly arcuate shape to add contour to a pattern of LEDs disposed on the board. However, a rigid flex board only allows for a slight amount of flexing, which may not be adequate for a lens with more than a slight curve because the LEDs may still not be close enough to the interior surface of the curved lens. If the LEDs are located too far from the interior surface of the lens, the light output may appear dull, which may be undesirable.
The present invention provides a non-planar LED arrangement for use in a lamp that is simple and cost-effective to produce, without compromising the amount of light that is visible through a lamp lens.
In one form, a substrate assembly for use in a lamp comprises a main printed wiring board and a standoff printed wiring board. The main printed wiring board has a main surface and at least one first light-emitting diode (LED) package disposed on the main surface and electrically connected thereto. The standoff printed wiring board is disposed on the main surface of the main printed wiring board. The standoff printed wiring board has at least one second LED package disposed thereon.
In another form, a substrate assembly for use in a lamp comprises a main printed wiring board and a standoff board. The main printed wiring board has a main surface and at least one first LED package disposed on the main surface and electrically connected thereto. The standoff board is disposed on the main surface of the main printed wiring board. The standoff board has at least one second LED package disposed thereon and conductors to provide an electrical connection between the at least one second LED package and the main printed wiring board.
In yet another form, a lamp for use in a motor vehicle comprises a main printed wiring board, a standoff board, and a lens. The main printed wiring board has at least one first LED package disposed thereon and electrically connected thereto. The standoff board is disposed on the main surface of the main printed wiring board. The standoff board has at least one second LED package disposed thereon and conductors to provide an electrical connection between the at least one second LED package and the main printed wiring board. The lens has a curved surface and is disposed adjacent to the first and second LED packages. The at least one second LED package is located farther from the main circuit board than the at least one first LED package. Each of the first and second LED packages is located to correspond to the curved surface of the lens.
Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification.
Referring now to
The substrate assembly 14 includes a main printed wiring board 16 and a standoff board 18. A first set of LED packages 20 are disposed on a main surface of the main printed wiring board 16 and are electrically connected thereto. Another LED package 22 is disposed on the standoff board 18. In this embodiment, the standoff board 18 and LED package 22 are located between the first set of LED packages 20 along the main printed wiring board 16. Because the LED package 22 is located on the standoff board 18, it is farther away (at a z-height) from the main printed wiring board 16 than the first set of LED packages 20. The location or z-height of each LED package 20, 22 corresponds to the curved surface of the lens 12. The LED packages 20, 22 are located a substantially equal distance from the interior 11 of the lens 12, even though the lens 12 has a curved surface.
It should be understood that the substrate assembly 14 could have other combinations of LED packages 20, 22 and standoff boards 18, without falling beyond the spirit and scope of the present invention. For example, other standoff boards 18 may be used to elevate LEDS 22 closer to the interior surface of the lens 12, which may be particularly useful if the lens 12 was provided having a different curvature than that shown in
The main printed wiring board 16 could optionally have apertures 24 for attachment of other components or to attach the lamp 10 to another object. Likewise, the standoff board 18 could also have apertures for attachment (not shown).
The standoff board 18 is disposed on the main printed wiring board 16 and electrically connected thereto. The standoff board 18 provides an electrical connection between the LED package 22 and the main circuit board 16. The standoff board 18, like the main printed wiring board 16, could also be a printed wiring board, such that the standoff board 18 comprises dielectric material and conductive traces. For example, the standoff board 18 could be a standard FR-4 printed wiring board. Instead of being a printed wiring board, the standoff board 18 could merely comprise a non-conductive substrate and conductors to provide an electrical connection between the LED package 22 and the main printed wiring board 16, which will be described in more detail with reference to
In the embodiment of
Now with reference to
In this embodiment, a surface mount LED package 222 is soldered to connect LED leads 238 to conductor pads 240 located on the second surface 236 of the standoff board 218. The conductor pads 240 electrically connect the LED leads 238 to the conducting material that extends through the holes 232. The conducting material is electrically connected to conductor pads 242 located on the first surface 234 of the standoff board 218. Each conductor pad 242 is soldered to a land, conductor pad, or other conducting portion (not shown) located on or in the main printed wiring board 216. This series of electrical connections results in an electrical connection between the LED package 222 and the main printed wiring board 216.
Referring now to
The standoff board 318 has portions forming a plurality of castellations 332 along at least one side 319 of the standoff board 318. In contrast to the holes 232 of
A surface mount LED package 322 is soldered to connect LED leads 338 to conductor pads 340 located on the second surface 336 of the standoff boards 318. The conductor pads 340 electrically connect the LED package 322 to the conducting material that extends along the castellations 332. The conducting material is electrically connected to conductor pads 342 located on the first surface 334 of the standoff board 318. Each conductor pad 342 (and/or the conducting material located in each castellation 332) is soldered to a land, conductor pad, or other conducting material (not shown) located on or in the main printed wiring board 316. This series of electrical connections results in an electrical connection between the LED package 322 and the main printed wiring board 316. The castellations 332 could be provided in addition to the holes 232 of
It should be understood that the standoff board 18, 118, 218, 318 could provide any other suitable configuration to electrically connect an LED package 22, 122, 222, 322 to a main printed wiring board 16, 116, 216, 316. For example, standoff board 18, 118, 218, 318 could carry the electrical connection via traces (not shown) located in and/or on the standoff board 18, 118, 218, 318. Further, the LED package 22, 122, 222, 322 need not be a surface mount device, but could be any suitable type of LED package 22, 122, 222, 322.
The present invention provides a non-complex solution to provide a three-dimensional arrangement of LED packages. Some embodiments of the invention may also be manufactured relatively simply. For example, a high temperature solder could be used to solder the standoff board 18, 118, 218, 318 to the main printed wiring board 16, 116, 216, 316 in a first stage. Then, in a second stage, a low temperature solder could be used to attach the LED package 22, 122, 222, 322 to the standoff board 18, 118, 218, 318. In the alternative, the LED package 22, 122, 222, 322 could first be soldered to the standoff board 18, 118, 218, 318 using a high temperature solder, and in a second stage, the standoff board 18, 118, 218, 318 could be soldered to the main printed wiring board 16, 116, 216, 316 using a low temperature solder. In another alternative, low temperature solder (or high temperature solder) could be used for soldering both the standoff board 18, 118, 218, 318 and the LED package 22, 122, 222, 322. It should be understood that any other suitable manufacturing process could be used, without falling beyond the spirit and scope of the present invention.
As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from the spirit of this invention, as defined in the following claims.
