Standard for LED Star Boards? - Page 1
Forum section: electronics / projects

author: X
author_rank: Regular Contributor
timestamp: July 04, 2018, 12:53:23 am
content: I have been looking at purchasing some moderate power UV LEDs for a bit of experimentation.I notice a lot of these LEDS have the option of either the SMD package on its own, or pre-assembled on a star board.I thought the star board was some kind of hobbyist-friendly or prototype-friendly format, or something from Cree (or did someone else first start this whole star board form factor?) but it seems that some high-end and expensive LEDs also come within this format:9W output 365nmhttps://www.digikey.com/product-detail/en/luminus-devices-inc/SBM-120-UV-R34-I365-22/SBM-120-UV-R34-I365-22-ND/765325370mW output 280nmhttps://www.digikey.com/product-detail/en/rayvio-corporation/RVXP4-280-SB-077132/1807-1019-ND/7363774All the star boards from different manufacturers seem to have exactly the same physical dimensions, so I am inclined to believe that this is a standard of some sort. In fact, the only variance umong manufacturers are the connecting pads on the edges of the star boards.I have been looking all around for what actually uses these "standard" LED star boards, and if there is indeed a standard, but all I get is videos, links, and forum posts about people who wire up these boards as a hobby, or advertisements for more LEDs mounted on said boards.Are there manufacturers who specialise in accessories (heatsinks, lenses, enclosures) that are designed to fit this "standard" star board form factor?

author: DaJMasta
author_rank: Super Contributor
timestamp: July 04, 2018, 03:00:24 am
content: Not an expert, but they are very common and are supplied in official configurations (whether or not they're manufactured by the same company aside). It's my understanding that basically, they are supplied for easy integration with low-volume products, but generally if you're designing for tens or hundreds of thousands of units, the extra mounting requirements make them not worthwhile, so you just buy the LEDs themselves and build your own board/heatspreader combo.The mounting should be as simple as a screw on either side in the notches, so two diagonal holes directly into a heatsink, and the boards themselves usually have a metal core for good thermal contact between the LED on top and the heatsink they're mounted to. The lenses are generally fit to the LED's built in lens, but often are as wide as a star board so they can be put next to each other at the same density as the star boards themselves. Since they're basically individually wired when attached to a heatsink, the enclosure is just a matter of holding the heatsink and lenses in the right place, it doesn't have so much to do with the boards themselves.

author: X
author_rank: Regular Contributor
timestamp: July 05, 2018, 11:05:56 pm
content: I'm aware of their ease of use and advantages for low-volume production. Even a nice advantage for thermal management as it acts as a heat spreader.I am also aware of how common they are, and noted that in my post.What I was asking about is whether there is a specific standard for this, since every manufacturer that offers a star board form factor uses exactly the same dimensions. What I wanted to know is whether the star form is a trademark/patent that belongs to one PCB manufacturer in the world, or is there are some professional or industry-level accessories that are made to suit this form factor, hence the (possibly de-facto) standard dimensions for every star board from different manufacturers I've noticed. A bit like TO-xxx transistor and IC packages. Different pins, but exactly the same form factor.I'm looking into buying a UV LED in star-board configuration (370nm or lower) but I want to know what else can be done with it.For example, lenses I see from manufacturers only seem to specify suitability for their own LED lines.

author: DaJMasta
author_rank: Super Contributor
timestamp: July 05, 2018, 11:24:52 pm
content: At least on the lens side, I think you see that because they are matched to the form factor of the LED package, which can differ even when using the star board. I haven't seen an LED lens than actually interacts with the board - there's usually a secondary holder either for holding all the lenses or attaching directly to the star board. The lens design also corresponds to the integrated lens/field of view of the LED package, so I wouldn't be surprised if there were LEDs from the same manufacturer and form factor that needed different lenses for the same beam angle.I don't think the star boards are a dedicated standard - a couple searches show 0.2mm variation in specified width and several mm worth of thickness variation, from ones without metal cores to aluminum and even thicker copper cores, that said, they do seem to be generally the same design. There are also many reputable brands making star boards without any trademark or identifying patent information, so I don't think the design is a restricted one. I can't comment on the history of their development, but they are in many cases practically interchangeable, and there are housing devices that will fit many kinds of LEDs/star boards. If you google "TE 114-13227" you should get an app note outlining a holder with an integrated lens designed for accommodating a number of star boards and configurations. While it probably can't do all of them, it's designed to be compatible so it should give you an idea of how interchangeable they generally are. Maybe if you had a specific LED/board in mind, people would be able to comment if they had tried them with other configurations.